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S Beck

Publications and source records attributed to S Beck.

At least 19 recordsLinked to original sources
PubMed1992

DNA sequence analysis of 66 kb of the human MHC class II region encoding a cluster of genes for antigen processing.

The genomic sequence of a 66,109 bp long region within the human MHC has been determined by manual and automated DNA sequencing. From cDNA mapping and sequencing data it is known that this region contains a cluster of at least four genes that are believed to be involved in antigen processing. Here, we describe the genomic organization of these genes, which comprise two proteasome-related genes (LMP2 and LMP7), thought to be involved in the proteolytic degradation of cytoplasmic antigens and two ABC transporter genes (TAP1 and TAP2), thought to be involved in pumping of the degraded peptides across the endoplasmic reticulum membrane. Analysis of the sequence homology and the intron/exon structures of the corresponding genes suggests that one gene pair arose by duplication from the other. Comparison of the available sequence data from other organisms shows striking conservation (70 to 84%) of this gene cluster in human, mouse and rat. The presence of several potential interferon stimulated response elements (ISREs) is in agreement with the experimentally observed up-regulation of these genes with gamma-interferon.

Amino Acid Sequence↗
PubMed1992

Field inversion gel electrophoresis in denaturing polyacrylamide gels.

The velocities of single stranded DNA molecules in denaturing polyacrylamide gels during symmetric and asymmetric field inversion were measured at different pulse times and gel concentrations. Under the conditions chosen in our study, pulse times as short as a few milliseconds lead to a retardation of DNA molecules larger than 400 bases. We found that a field inversion with an electric field in the forward direction of about double the strength of that applied in the backward direction is a good compromise between the degree of retardation, the temperature control requirements and the run time of the gel.

DNA, Single-Stranded↗
PubMed1992

Polymorphism in a second ABC transporter gene located within the class II region of the human major histocompatibility complex.

Recent studies have identified genes within the major histocompatibility complex (MHC) that may play a role in presentation of antigenic peptides to T cells. We have previously described RING4, a gene within the human MHC class II region that has sequence homology with members of the ABC ("ATP-binding cassette") transporter superfamily. We now report the nucleotide sequence of RING11, a second ABC transporter gene located approximately 7 kilobases telomeric to RING4, RING11 is gamma-interferon inducible, a property shared with other genes involved in antigen presentation. Comparison between the amino acid sequences of RING11 and RING4 reveals strong homology. We propose that they form a heterodimer that transports peptides from the cytoplasm into the endoplasmic reticulum. We have identified two RING11 alleles, which differ in the length of their derived protein sequence by 17 amino acids. The more common of these alleles is present in a Caucasoid population at a frequency of 79%.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1992

Magnetic bead purification of M13 DNA sequencing templates.

A method for the preparation of multiple M13 DNA sequencing templates is described. No phenol extraction is required and the procedure can be carried out in Eppendorf tubes or 96-well microtiter plates. Starting with a phage supernatant, the entire procedure is carried out in the same reaction vessel and all separation steps are based on a novel application of magnetic bead separation. The design of a 96-well magnetic separator is presented and the application of the method for large-scale sequencing is discussed.

Bacteriophages↗
PubMed1992

Interferon-gamma may enhance infection of blood-derived macrophages with HIV-1 in the presence of HIV-positive serum.

HIV multiplication in blood-derived macrophages was slightly inhibited by pretreatment of cells with interferon-gamma or by preincubation of virus with serum containing antibodies against HIV. When these pretreatments were combined, the HIV titres observed a short time after infection were enhanced. This effect was blocked by antibodies against Fc receptors but not by antibodies against CD4 receptors. Interferon enhanced the expression of Fc receptors on macrophages. The results indicate that IFN-gamma, in appropriate combinations with HIV-antibody-containing human serum, may enhance the rate of HIV infection of macrophages.

Antibodies↗
PubMed1992

A homologue of the Drosophila female sterile homeotic (fsh) gene in the class II region of the human MHC.

The RING3 gene maps in the class II region of the human major histocompatibility complex, at a CpG island distal of the HLA-DNA gene. RING3 cDNAs were obtained from a T cell cDNA library and the longest (4 kb) was sequenced. The sequence contained an open reading frame encoding a protein of 754 amino acids. A screen of protein databases revealed striking homology between the RING3 protein and the Drosophila female sterile homeotic gene (fsh) which is implicated in the establishment of segments in the early embryo. Partial sequence homology was also observed with some other proteins involved in cell cycle control (CCG1), cell division (ftsA) and regulation of cell growth (gamma interferons). This highly conserved gene may play an important role in human development. In addition, its location in the MHC class II region may be related to some HLA-associated diseases.

Amino Acid Sequence↗
PubMed1991

Second proteasome-related gene in the human MHC class II region.

Antgen processing involves the generation of peptides from cytosolic proteins and their transport into the endoplasmic reticulum where they associate with major histocompatibility complex (MHC) class I molecules. Two genes have been identified in the MHC class II region, RING4 and RING11 in humans, which are believed to encode the peptide transport proteins. Attention is now focused on how the transporters are provided with peptides. The proteasome, a large complex of subunits with multiple proteolytic activities, is a candidate for this function. Recently we reported a proteasome-related sequence, RING10, mapping between the transporter genes. Here we describe a second human proteasome-like gene, RING12, immediately centromeric of the RING4 locus. Therefore RING12, 4, 10 and 11 form a tightly linked cluster of interferon-inducible genes within the MHC with an essential role in antigen processing.

Amino Acid Sequence↗
PubMed1991

A proteasome-related gene between the two ABC transporter loci in the class II region of the human MHC.

It is now possible to paint a detailed picture of how cytoplasmic proteins are handled by the immune system. They are apparently degraded in the cytoplasm into peptides. These are then transported into the endoplasmic reticulum where they encounter class I major histocompatibility complex (MHC) molecules. Once loaded with peptide, the HLA molecules move through the Golgi apparatus to the cell membrane. Until recently, it had not been established how peptides without signal sequences cross the ER membrane. However, a number of papers have now described a pair of membrane transporter genes of the ABC (ATP-binding cassette) super-family which are attractive candidates for this function. Both transporter genes, which may encode two halves of a heterodimer, are situated in the class II region of the MHC. There is evidence that other putative components of the processing machinery, the LMPs (low molecular mass polypeptides), are also encoded in the MHC. Similarities between the properties of the LMPs and a large intracellular protease complex, called proteasome, have led to the suggestion that LMPs are involved in processing antigens. We have now identified a human gene with sequence homology to proteasome components. Remarkably, this gene maps between the two putative peptide transporter genes.

Amino Acid Sequence↗
PubMed1991

Trimethoprim-sulfamethoxazole oral desensitization in hemophiliacs infected with human immunodeficiency virus with a history of hypersensitivity reactions.

Hemophiliacs infected with human immunodeficiency virus with a history of hypersensitivity reaction to a combination product of trimethoprim and sulfamethoxazole were desensitized orally. Six of the seven patients included in the study successfully completed the desensitization protocol and received trimethoprim-sulfamethoxazole for 5 to 7 months after desensitization (mean length of treatment, 5.7 months) for prophylaxis of Pneumocystis carinii pneumonia. The small number of patients and the short follow-up allow us to suggest that oral desensitization may be an effective and inexpensive means to treat hemophiliacs infected with human immunodeficiency virus with trimethoprim-sulfamethoxazole as prophylaxis against Pneumocystis carinii pneumonia.

AIDS-Related Opportunistic Infections↗
PubMed1991

Amino acid sequence of mouse tenascin and differential expression of two tenascin isoforms during embryogenesis.

We have isolated cDNA clones for mouse tenascin and analyzed expression of tenascin mRNAs during embryonic development of the kidney and gut. The deduced amino acid sequence of the mouse tenascin cDNAs shows a modular structure of repeats similar to chicken and human tenascin. In mouse there are 14.5 cysteine-rich repeats with similarity to the EGF repeat, followed by several repeats with similarity to the type III repeat of fibronectin. A longer variant contains 13 fibronectin type III repeats, whereas a shorter splice variant of mouse tenascin lacks the 5 type III repeats that occur directly after the fifth repeat in the longer variant. Contrary to the chicken and human sequences, mouse tenascin does not contain an RGD sequence in the third type III repeat implicated in cell attachment, or in any other positions. In Northern hybridizations to RNA from primary embryonic fibroblasts, the cDNA clone M 20/1 detects two mRNAs with sizes close to 6 and 8 kb. This, and the other data presented here suggest that the two major mouse tenascin polypeptides arise through an alternative RNA splicing. The two major mRNAs are differentially expressed during development. The 8-kb mRNA is more prominent than the 6-kb mRNA throughout prenatal kidney development, but during postnatal development the ratio of the two mRNAs changes. A different expression pattern is seen in the developing gut where the 6-kb mRNA predominates during embryogenesis with the 8-kb mRNA appearing later. The mRNA data of the developing gut correspond with previous protein data, which showed that the shorter Mr 210,000 polypeptide predominates during earlier developmental stages and the larger Mr 260,000 polypeptide appears later in the embryonic gut (Aufderheide, E., and P. Ekblom. 1988. J. Cell Biol. 107:2341-2349).

Amino Acid Sequence↗
PubMed1991

The DNA sequence of the human cytomegalovirus genome.

In the first part of this article we review what has been learnt from the analysis of the sequence of HCMV. A summary of this information is presented in the form of an updated map of the viral genome. HCMV is representative of a major lineage of herpesviruses distinct from previously sequenced members of this viral family and demonstrates striking differences in genetic content and organization. The virus encodes approximately 200 genes, including nine gene families, a large number of glycoprotein genes, and homologues of the human HLA class I and G protein-coupled receptor genes. The HCMV sequence thus provides a sound basis for future molecular studies of this highly complex eukaryotic virus. The second part discusses the practical rate of DNA sequencing as deduced from this and other studies. The 229 kilobase pair DNA genome of human cytomegalovirus (HCMV) strain AD169 is the largest contiguous sequence determined to date, and as such provides a realistic benchmark for assessing the practical rate of DNA sequencing as opposed to theoretical calculations which are usually much greater. The sequence was determined manually and we assess the impact of new developments in DNA sequencing.

Base Sequence↗
PubMed1991

An HCMV reading frame which has similarity with both the V and C regions of the TCR gamma chain.

Human cytomegalovirus (HCMV) is a member of the herpes virus family and is characterized by widespread infection, latency, persistence and reactivation and is a serious pathogen particularly of immunosuppressed patients. Previously HCMV was shown to encode a glycoprotein homologous to the MHC class I antigens. We report here that HCMV may encode another glycoprotein similar to another sub-group of the Ig superfamily. This putative glycoprotein gene shows similarity to both the constant and variable regions of the human T cell receptor gamma chain (TCR gamma). The level of homology is low but may be of interest as the predicted gene might have some role in virus infection or immune evasion.

Amino Acid Sequence↗