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Results for “TCR specificity prediction”

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At least 109 records · Page 6Linked to original sources

PubMed1995

Hepatosplenic gamma-delta T-cell malignant lymphoma: report of the first case in childhood, including molecular minimal residual disease follow-up.

We report the first case of T-cell gamma delta+ hepatosplenic malignant lymphoma in childhood. Tumour-specific oligoprobes were developed against the single V1-J1 rearrangement of the delta T-cell receptor (TCR) gene in order to perform minimal residual disease (MRD) studies. Molecular analysis in serial bone marrow samples proved to be of predictive value concerning the clinical outcome. Clonotypic DNA was not detected in peripheral blood during the course of the disease until a refractory terminal leukaemic phase took place 18 months after the diagnosis. This case demonstrates the usefulness of MRD studies to monitor the course of disease in at least some subsets of peripheral T-cell lymphomas.

Base Sequence↗

PubMed1999

[Dobutamine stress echocardiography in prediction of dilated cardiomyopathy in patients with allergic myocarditis].

Total contractility reserve (TCR) and role of TCR in prediction of dilated cardiomyopathy (DCM) were evaluated in patients with infectious allergic myocarditis (IAM) by means of stress-echocardiography with dobutamine. Systolic function of the left ventricle (LV) appeared activated in different degree in relatively equal baseline low levels of LV contractility. IAM patients with reduced reserve of TCR are characterized by low increment of LV contractility under stress test and frequent onset of DCM. The increment of ejection fraction in low-dose dobutamine stress echocardiography was found informative in prediction of DCM development, highly sensitive and specific.

Adult↗

PubMed2026

Real-World Experience With TRBC1 Immunohistochemistry Across Cutaneous T-Cell Lymphoma Subtypes: A Large Cohort Study.

T-cell receptor β-chain constant region 1 (TRBC1) immunohistochemistry identifies clonal αβ T-cell populations on tissue sections, but its real-world performance across cutaneous T-cell lymphoma (CTCL) and related infiltrates is uncharacterized. The analytic cohort comprised 665 biopsies (566 patients) with paired T-cell receptor (TCR) clonality testing, classified clinicopathologically as mycosis fungoides (MF; MF-Patch, MF-Plaque, MF-Tumor, and MF-Folliculotropic); MF or Sézary syndrome; primary cutaneous small or medium T-cell lymphoproliferative disorders (LPDs); other CTCL-cutaneous LPDs; or reactive. At the primary <15%/>85% threshold, TRBC1 IHC achieved 85.8% sensitivity (337/393), 79.8% specificity (217/272), 86.0% positive and 79.5% negative predictive value, and 83.3% accuracy. Sensitivity was lowest in MF-Patch (84.2%). Three-reader agreement (Fleiss κ = 0.943) fell to κ = 0.776 in 176 reflexed biopsies, with disagreement concentrated on MF-Patch and CD30-positive LPDs. Monotypic TRBC1 predicted neoplasia, with odds rising with infiltrate density: MF-Patch (odds ratio, 5.41), MF-Plaque (10.40), MF/Sézary syndrome with MF-Tumor (15.19), and CTCL-cutaneous LPD (18.16). Polytypic TRBC1 was associated with reactive disease (odds ratio, 53.65), effectively excluded clonality (negative likelihood ratio, 0.18), and was uniformly observed in an independent 270-biopsy reactive cohort. For observer-independent validation, digital image analysis-derived TRBC1 quantification (QuPath) was applied to a stratified random subset of 250 biopsies representative of the cohort's tumor-burden distribution. The digital read-tracked molecular clonality (85.1% sensitivity, 80.1% specificity against TCR; area under the curve, 0.842) agreed with the dermatopathologist's manual read in 87.6% of cases (κ = 0.752), with the data-derived cutoff matching the prespecified <15%/>85% threshold value. Discordance was directional for both manual scoring and digital quantification: in MF-Patch, 25 of 38 (65.8%) and 12 of 17 (70.6%) cases were polytypic with monoclonal TCR (false-negative-dominant); in reactive biopsies, 34 of 45 (75.6%) and 19 of 20 (95%) were monotypic with polyclonal TCR (false-positive-dominant). These findings support a TRBC1-first approach, reserving reflex TCR testing for borderline expression or clinicopathologic discordance, preserving diagnostic accuracy while reducing molecular testing and reimbursement-based costs.

Sézary syndrome↗

PubMed1998

Structural basis of specificity and degeneracy of T cell recognition: pluriallelic restriction of T cell responses to a peptide antigen involves both specific and promiscuous interactions between the T cell receptor, peptide, and HLA-DR.

TCR engagement of peptide-MHC class II ligands involves specific contacts between the TCR and residues on both the MHC and peptide molecules. We have used molecular modeling and assays of peptide binding and T cell function to characterize these interactions for a CD4+ Th1 cell clone, ESL4.34, which recognizes a peptide epitope of the herpes simplex type 2 virus virion protein, VP16 393-405, in the context of several HLA-DR alleles. This clone responded to VP16 393-405 in proliferation and cytotoxicity assays when presented by DRB1*0402, DRB1*1102, and DRB1*1301, which share a common amino acid sequence, ILEDE, at residues 67-71 in the alpha-helical portion of the DRbeta polypeptide, but not when presented by other DR4, DR11, and DR13 alleles that are negative for this sequence. Using a panel of APCs expressing DR4 molecules that were mutagenized in vitro at individual residues within this shared epitope and using peptide analogues with single amino acid substitutions of predicted MHC and TCR contact residues, a unit of recognition was identified dependent on DRbeta residues 67-71 and relative position 4 (P4) of the VP16 393-405 peptide. The interactions of this portion of the peptide-DR ligand with the ESL4.34 TCR support a structural model for MHC-biased recognition in some Ag-specific and alloreactive T cell responses and suggest a possible mechanism for autoreactive T cell selection in rheumatoid arthritis.

Alleles↗

PubMed1998

Point mutations in the beta chain CDR3 can alter the T cell receptor recognition pattern on an MHC class I/peptide complex over a broad interface area.

To study how the T cell receptor interacts with its cognate ligand, the MHC/peptide complex, we used site directed mutagenesis to generate single point mutants that alter amino acids in the CDR3beta loop of a H-2Kb restricted TCR (N30.7) specific for an immunodominant peptide N52-N59 (VSV8) derived from the vesicular stomatitis virus nucleocapsid. The effect of each mutation on antigen recognition was analyzed using wild type H-2Kb and VSV8 peptide, as well as H-2Kb and VSV8 variants carrying single replacements at residues known to be exposed to the TCR. These analyses revealed that point mutations at some positions in the CDR3beta loop abrogated recognition entirely, while mutations at other CDR3beta positions caused an altered pattern of antigen recognition over a broad area on the MHC/peptide surface. This area included the N-terminus of the peptide, as well as residues of the MHC alpha1 and alpha2 helices flanking this region. Assuming that the N30 TCR docks on the MHC/peptide with an orientation similar to that recently observed in two different TCR-MHC/peptide crystal structures, our findings would suggest that single amino acid alterations within CDR3beta can affect the interaction of the TCR with an MHC surface region distal from the predicted CDR3beta-Kb/VSV8 interface. Such unique recognition capabilities are generated with minimal alterations in the CDR3 loops of the TCR. These observations suggest the hypothesis that extensive changes in the recognition pattern due to small perturbations in the CDR3 structure appears to be a structural strategy for generating a highly diversified TCR repertoire with specificity for a wide variety of antigens.

Amino Acid Sequence↗

PubMed1993

Identification of conserved T cell receptor CDR3 residues contacting known exposed peptide side chains from a major histocompatibility complex class I-bound determinant.

We have analyzed the T cell receptor (TCR) repertoire found in the major histocompatibility complex class I-restricted cytotoxic T lymphocyte (CTL) response to the protein ovalbumin (OVA). Despite skewing towards the expression of V beta 5.2+TCR by OVA-specific CTL from C57BL/6 mice, we found a relatively high degree of diversity in V(D)J usage in both TCR alpha- and beta-chains. Closer examination showed that the majority of these sequences encoded negatively and positively charged residues at their respective TCR alpha- and beta-chain VJ or VDJ junctions. These junctions form the third complementarity-determining regions (CDR3) of the TCR polypeptides involved in the direct interaction with the class I-bound peptide. Crystallographic analyses of Kb-peptide complexes predict that the major determinant from OVA, peptide OVA257-264 (SIINFEKL), contains two exposed charged side chains which can contact the TCR. These are the negatively charged glutamic acid at determinant position 6 (P6) and the positively charged lysine at P7. To examine whether the TCR alpha-chain makes contact with P7 lysine, we established a single chain TCR transgenic C57BL/6 mouse line where all T cells express a TCR beta-chain derived from the V beta 5.2+ clone B3. OVA-specific T cells derived from in vivo primed transgenic mice preferentially expressed TCR alpha-chains that also contained negatively charged junctional residues despite some further variation in V alpha and J alpha sequences. Stimulation of naive TCR beta-chain transgenic T cells with a P7 substitution peptide analogue induced a T cell response that was no longer cross-reactive with the wild-type OVA257-264 determinant, suggesting that the TCR alpha-chain from the T cell clone B3 can determine the specificity for this residue. Consequently, these results reveal the existence of conserved residues in the CDR3 of TCR alpha- and beta-chains specific for OVA257-264 and identify their possible orientation over the peptide-class I complex.

Amino Acid Sequence↗

PubMed1991

Crosslinked staphylococcal enterotoxin B stimulates CD8+ T cells only in the presence of unlinked costimulator signals.

The superantigen staphylococcal enterotoxin B (SEB) binds to class II MHC expressing cells and subsequently causes selective activation of T cells carrying appropriate T cell receptor (TCR) V beta chains. Apparently SEB acts as a bifunctional molecule by bridging class II MHC structures with the appropriate TCR-V beta chains. This assumption predicts that immobilized SEB ought to stimulate purified, class II MHC negative murine T cells. We show here that immobilized SEB lacks the ability to trigger murine CD8 T cells. Responsiveness obtained at a high T cell concentration is due to contaminating class II MHC-positive lymphocytes. Complementation of the culture system with syngeneic irradiated B cells blasts effectively restores responsiveness. The proliferating cells exhibit SEB specific cytotoxicity and a bias for V beta 8 expression. Since no evidence for leakiness of SEB covalently bound to sephadex beads was obtained, the data imply that immobilized SEB in fact binds to the TCR of T cells expressing the appropriate V beta chains. However, for primary activation additional costimulatory signals are required which can be provided in an unlinked fashion by activated B cells. Resting B cells are activated by immobilized SEB to cells expressing high costimulator activity. As such, the data point out a third function of SEB.

Animals↗

PubMed1998

Structural aspects of the interaction between heterogeneic human papillomavirus type 1 E4-specific T cell receptors and the same peptide/HLA-DQ8 complex.

TCR usage has been studied in a panel of Th cell clones specific for the same peptide epitope (P N S Q D R G R P R R S D), derived from the human papillomavirus type 1 (HPV1) E4 protein, and restricted through HLA-DQ8. After identifying the V, D, and J genes used by the TCRs and sequencing across the V(D)J junctions, five different alpha-chain sequences and five different beta-chain sequences, comprising six independent clones, were identified. A structural model of our E4 peptide/HLA-DQ8 complex predicted that the guanidinyl side chain on the arginine residue at position 6 of the peptide could exist in different orientations. An intramolecular interaction between this arginine and the glutamine residue at position four appeared to control this orientation. Interacting HPV1 E4-specific TCRs would therefore have to recognize the complex in different conformations, and molecular modeling of the TCRs suggested that this could be achieved by changing the dimensions of the central pocket formed where the CDR3 loops of the TCR alpha- and beta-chains converge. It is known that interactions between bound peptide and amino acid residues lining the peptide-binding cleft of HLA molecules are important for determining the conformation and orientation of the peptide/MHC complex. The suggestion here that intramolecular interactions between amino acids of close proximity on the bound peptide are also important adds a further level of complexity to the mechanism by which TCRs interact with Ag.

Amino Acid Sequence↗

PubMed1995

Characterization of diverse primary herpes simplex virus type 1 gB-specific cytotoxic T-cell response showing a preferential V beta bias.

The glycoprotein B (gB) from herpes simplex virus type I is a major target of cytotoxic T lymphocytes (CTL) in C57BL/6 mice. The majority of these T cells are directed to a single Kb-restricted determinant, gB498-505. We have analyzed the T-cell receptor (TCR) usage in gB-specific CTL lines derived shortly after virus infection. The CTL populations preferentially used two V beta regions, a dominant V beta 10 element and a subdominant V beta 8 element. Detailed sequence analysis revealed considerable TCR beta-chain heterogeneity despite a striking level of predicted amino acid conservation at the V beta-D beta junction. This junction forms part of the third hypervariable loop of the TCR thought to directly contact the major histocompatibility complex-bound antigenic peptide. The results reveal considerable diversity within the primary T cells responding to a single viral determinant while still maintaining a high degree of TCR V beta bias and sequence conservation at the V-D-J junction.

Amino Acid Sequence↗

PubMed1992

Molecular components of T-cell recognition.

We review recent data that increase our understanding of the ternary complex of the T cell receptor (TCR), antigenic peptides, and molecules of the major histocompatibility complex (MHC). Studies using synthetic peptide analogs for T-cell antigens have identified peptide residues that appear to interact with the MHC molecule and/or the TCR. The logical extension of these studies, using a complete replacement set of peptide analogues for a model peptide antigen, has more precisely defined the biochemical character of putative MHC and TCR contact residues, and indicated that the TCR is highly sensitive to subtle changes in peptide conformation. Insight into the binding site for peptide on the TCR has recently come from variant peptide immunization of TCR single-chain transgenic mice. These experiments indicate that residues encoded by the V(D)J junctions of both TCR chains contact peptide directly. TCR-MHC contacts have also been studied, using in vitro-mutagenized MHC molecules, particularly those altered at residues predicted to point "up," toward the TCR. These studies reveal that TCR-MHC contacts appear to be quite flexible, and vary between even closely related TCRs. A measure of the affinity of TCR for peptide/MHC complexes has come from competition experiments using soluble MHC complexed with specific peptides. This affinity, with a KD of 5 x 10(-5) M, is several orders of magnitude lower than that of most antibodies for their protein antigens and suggests that the sequence of events leading to T-cell activation begins with antigen-independent adhesion.

Amino Acid Sequence↗

PubMed1991

A thymus-specific member of the HMG protein family regulates the human T cell receptor C alpha enhancer.

The human T cell-specific transcription factor TCF-1 alpha plays a key role in the tissue-specific activation of the T cell receptor (TCR) C alpha enhancer and binds to pyrimidine-rich elements (5'-PyCTTTG-3') present in a variety of other T cell-specific control regions. Using amino acid sequence information derived from the DNA affinity-purified protein, we have now isolated cDNA clones encoding TCF-1 alpha. The TCF-1 alpha cDNA contains a single 68-amino-acid domain that is homologous to a region conserved among high-mobility group (HMG) and nonhistone chromosomal proteins. Expression of full-length and mutant cDNA clones in bacteria reveal that the single HMG motif, which is predicted to contain two extended alpha-helical segments, is sufficient to direct the sequence-specific binding of TCF-1 alpha to DNA. Northern blot experiments demonstrate further that TCF-1 alpha mRNA is highly tissue specific, found primarily in the thymus or T cell lines. The immature CEM T cell line expresses relatively low levels of TCF-1 alpha mRNA, which are increased upon activation of these cells by phorbol esters. Interestingly, the cloned TCF-1 alpha protein is a potent transcriptional activator of the human TCR alpha enhancer in nonlymphoid cell lines, whereas the activity of the endogenous protein in T cell lines is strongly dependent on an additional T cell-specific protein that interacts with the core enhancer. TCF-1 alpha is currently unique among the newly emerging family of DNA-binding regulatory proteins that share the HMG motif in that it is a highly tissue-specific RNA polymerase II transcription factor.

Amino Acid Sequence↗

PubMed1990

Analysis of peptide residues interacting with MHC molecule or T cell receptor. Can a peptide bind in more than one way to the same MHC molecule?

It has generally been assumed implicitly that one can define amino acid residues of a T cell antigenic determinant peptide that interact with the MHC molecule, i.e., residues that form the "agretope." However, if the same peptide can be seen in different conformations or orientations in the same MHC molecule by different T cells, then we would predict that some residues would appear to interact with the TCR of one T cell clone but with the MHC molecule as the peptide is seen by another T cell clone. To test this hypothesis, we synthesized 36 analogue peptides of an immunogenic fragment (P133-146) of sperm whale myoglobin with three different substitutions for each of 12 amino-acid residues and analyzed the role of each residue for I-Ed-binding and for activation of two Th clones, 14.1 and 14.5, specific for the peptide. The two T cell clones showed slightly different fine specificity from each other in that the truncated peptide P136-144 could stimulate 14.5 but not 14.1. The binding activity of nonstimulatory analogues to the I-Ed molecule was measured by functional inhibition analyses using truncated wild-type peptides as stimulators and nonstimulatory analogues as inhibitors. Paradoxical results were obtained that could not be explained by the peptide binding in a single way to the same I-Ed molecule. Some residues appeared to reciprocally reverse their roles for binding to I-Ed vs binding to the TCR when assessed using T-cell clone 14.5 compared to clone 14.1. These results fit the prediction of the above hypothesis and indicate the possibility that the same peptide, P133-146, can bind in more than one way to the same Ia molecule. The T cell clones, 14.1 and 14.5, appear to recognize different P133-146-I-Ed complexes in which the peptide is bound differently. Moreover, a given residue may not have a unique function of always interacting with the MHC molecule or TCR, but may change from one role to the other as it is presented to different T cells.

Amino Acid Sequence↗

PubMed1990

The presumptive CDR3 regions of both T cell receptor alpha and beta chains determine T cell specificity for myoglobin peptides.

The T cell receptor alpha/beta (TCR-alpha/beta) is encoded by variable (V), diversity (D), joining (J), and constant (C) segments assembled by recombination during thymocyte maturation to produce a heterodimer that imparts antigenic specificity to the T cell. Unlike immunoglobulins (Igs), which bind free antigen, the ligands of TCR-alpha/beta are cell surface complexes of intracellularly degraded antigens (i.e., peptides) bound to and presented by polymorphic products of the major histocompatibility complex (MHC). Therefore, antigen recognition by T cells is defined as MHC restricted. A model has been formulated based upon the similarity between TCR-alpha/beta V region and Ig Fab amino acid sequences, and the crystal structure of the MHC class I and Ig molecules. This model predicts that the complementarity determining regions (CDR) 1 and 2, composed of TCR V alpha and V beta segments, primarily contact residues of the MHC alpha helices, whereas V/J alpha and V/D/J beta junctional regions (the CDR3 equivalent) contact the peptide in the MHC binding groove. Because polymorphism in MHC proteins is limited relative to the enormous diversity of antigenic peptides, the TCR may have evolved to position the highly diverse junctional residues (CDR3), where they have maximal contact with antigen bound in the MHC peptide groove. Here, we demonstrate a definitive association between CDR3 sequences in both TCR alpha and beta chains, and differences in recognition of antigen fine specificity using a panel of I-Ed-restricted, myoglobin-reactive T cell clones. Acquisition of these data relied in part upon a modification of the polymerase chain reaction that uses a degenerate, consensus primer to amplify TCR alpha chains without foreknowledge of the V alpha segments they utilize.

Amino Acid Sequence↗

PubMed1994

Residues outside of the HLA-A2 peptide-binding groove can abrogate or enhance recognition of influenza virus matrix peptide pulsed cells by cytotoxic T lymphocytes.

An examination of the crystal structure of HLA-A2.1 reveals two classes of residues on the class I MHC molecule that could affect CTL recognition: (1) those predicted to interact with the TCR directly; and (2) those that interact with bound peptides. To examine the role of individual TCR contacting residues, as well as residues not predicted to interact with bound peptide or the TCR, a panel of 28 HLA-A2 variants that differ from each other by a single amino acid substitution in either the alpha 1- or alpha 2-domain was utilized. Peptide titration, time course and cold target inhibition analysis of these targets showed that only the substitution of position 62 in the alpha 1-domain had a significant effect on recognition of the MHC-peptide complex by influenza matrix protein M1 (57-68) peptide-specific, HLA-A2.1-restricted CTL. In contrast, substitutions at positions 154, 162 and 163 in the alpha 2-domain abolished recognition by the same CTL. Additionally, substitutions at position 138 in the alpha 2-domain and positions 107 and 127 on the loops connecting the beta-strand in the alpha 2-domain were recognized in a more efficient, heteroclitic fashion. Overall, there was no direct correlation between the level of peptide binding to the variants and the level of T cell recognition of the variants. These results indicate that residues in the alpha 2-domain may be more important than residues in the alpha 1-domain in controlling TCR binding to the class I MHC molecule and suggest that the "footprint" of the TCR may be more extensive than previously predicted and encompass a broad region that extends beyond the alpha 2-helix. These findings also imply that the class I MHC molecule may exist in a "tipped" orientation on the cell surface during T cell recognition.

Amino Acid Sequence↗

PubMed2002

Disruption of the RanBP17/Hox11L2 region by recombination with the TCRdelta locus in acute lymphoblastic leukemias with t(5;14)(q34;q11).

The t(5;14)(q33-34;q11) translocation constitutes a recurrent rearrangement in acute lymphoblastic leukemia involving the T cell receptor (TCR) delta locus on chromosome 14. Breakpoint sequences of the derivative chromosome 5 were isolated by application of a ligation-mediated PCR technique using TCR delta-specific primers to amplify genomic DNA from the leukemic cells of a patient with t(5;14). Through exon trap analysis, we identified various putative exons of the chromosome 5 target gene of the translocation; compilation of sequence information of trapped exons and available expressed sequence tags (ESTs) from the GenBank database allowed us to assemble 1.2 kb of the cDNA. Full-length cDNAs were isolated from a human testis cDNA library and sequence analysis predicted a putative Ran binding protein, a novel member of the importin-beta superfamily of nuclear transport receptors, called RanBP17. The t(5;14) breakpoint maps to the 3' coding region of the gene. The breakpoint of a second t(5;14) positive patient was mapped about 8 kb downstream of the most 3' RanBP17 exon and 2 kb upstream of the first exon of the orphan homeobox gene, Hox11L2. In both cases TCR delta enhancer sequences are juxtaposed downstream of the truncated or intact RanBP17 gene, respectively on the derivative chromosome.

Acute Disease↗

PubMed1991

Radiation leukemia virus-induced T-cell lymphomas with common T-cell receptor variable region structure and similar binding specificity for retrovirus.

The 5C2 cell line was derived following culture of mouse spleen cells exposed in vivo and in vitro to radiation leukemia virus (RadLV) containing supernatants from the C6VL/1 T cell lymphoma. This cell line has been found to express an alpha beta T-cell receptor (TCR) identifiable with the Mab124-40 anti-clonotypic antibody which is specific for C6VL/1. It has been shown to be genetically and phenotypically distinct from C6VL/1 with a unique phenotype, i.e. CD4-, CD8-, CD3+, TCR-alpha beta. 5C2 has been shown to express high levels of alpha and beta chain mRNA and to utilize the same or similar V alpha and V beta region genes as C6VL/1. Whereas C6VL/1 binds cross-reactively to both RadLV/C6VL and an unrelated isolate RadLV/VL3, 5C2 has binding specificity for only RadLV/C6VL, which induced its proliferation. The anti-clonotypic antibody Mab124-40 specifically and completely inhibits binding of 5C2 to RadLV/C6VL at concentrations as low as 300 ng/ml. The 5C2 cell line can also be stimulated to increased proliferation by RadLV/C6VL. All of these data are consistent with the role of a TCR alpha beta heterodimer in binding and stimulation by RadLV and satisfy one prediction of the receptor-mediated leukemogenesis hypothesis that T-cell clones identifiable by their T-cell receptor clonotype may be targets for transformation by a particular retrovirus.

Animals↗

PubMed1994

Polymorphism detection and sequence analysis of human T-cell receptor V alpha-chain-encoding gene segments.

The T-cell receptor (Tcr) provides specificity for antigen recognition by its variable domain, primarily consisting of two germline encoded variable (V) region gene segments. Thus it has been suggested that inherited polymorphisms in the TCRV gene segments could contribute to differential immune responsiveness (e.g., autoimmunity) in human populations. In the present study, we have sought potentially functional polymorphisms in the germline TCRAV gene segments. Using denaturing gradient gel electrophoresis on polymerase chain reaction (PCR)-amplified products from the pooled DNA of many individuals, we identified polymorphisms in the TCRAV2S1, AV4S1, AV7S1, and AV8S1 gene segments. A complete DNA sequence analysis of these PCR products identified polymorphisms that affected amino acids in the predicted antigen-binding regions of the Tcr alpha chain, as well as polymorphisms in the introns. Genotype analysis of all nine DNA point mutations showed a 5%-50% range (averaging 35%) of minor allele frequencies, often resulting in individuals homozygous for the alternate allele forms. All possible haplotype combinations of the amino acid-affecting polymorphisms were found, indicating that in human populations there are a large number of different germline haplotypes encoding V gene segment alleles. These TCRAV coding region polymorphisms provide the rationale for, and allow the direct testing of, hypotheses concerning inherited polymorphisms within the T-cell receptor genes that may contribute to autoimmune susceptibility.

Base Sequence↗

PubMed1997

Expression, purification, and characterization of a murine CD4 fragment containing the first two N-terminal domains.

CD4 is a membrane glycoprotein on T lymphocytes that binds to the same peptide:major histocompatibility complex (MHC) class II molecules recognized by the antigen-specific T cell receptor (TcR). Recent evidence supports the importance of coaggregation of CD4 and TcR for effective T cell activation. Here, we report that a transfected Chinese hamster ovary (CHO) cell line expressing a murine CD4 fragment containing the first two N-terminal domains secretes both monomeric molecules and disulfide-linked multimers. Elimination of the predicted N-linked glycosylation site at residue 161 that is next to the fourth cysteine does not affect the formation of interchain disulfide bonds. N-Terminal amino acid sequencing of the purified CD4 fragment demonstrates that the leader signal sequence is properly cleaved off the expressed protein. Circular dichroism studies suggest that both monomeric and disulfide-linked proteins are folded as primarily beta-sheet.

Animals↗