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S Kvist

Publications and source records attributed to S Kvist.

At least 37 records · Page 2Linked to original sources
PubMed1986

A single nucleotide difference at the 3' end of an intron causes differential splicing of two histocompatibility genes.

The murine histocompatibility class I genes, H-2 Kb and Kk, display considerable homology at their 3' ends. In fact, from exon 5 to the termination codon, only two nucleotides differ between the two genes, one at the 5' end and the other at the 3' end of intron 7. Despite this similarity, the gene products have distinctly different mol. wts as determined by SDS-PAGE. By constructing two hybrid genes, pC2 and pC4, we demonstrated that it is the cytoplasmic parts of the antigens (encoded by exons 6-8) which are responsible for the major difference in mol. wt. We have used site-directed mutagenesis to change the two nucleotides in intron 7 of the H-2 Kk gene to those present in the H-2 Kb gene. S1 nuclease mapping has been used to identify the actual splice site of the authentic Kb and Kk genes, the hybrid genes and the mutagenized genes. We have shown that it is the 3' nucleotide difference, nine nucleotides upstream of the 3' splice site, which causes the different excision of intron 7 of the Kb gene. The 5' nucleotide difference does not alter the splicing. The choice of branch points and 3' splice signals for intron 7 of five H-2 class I genes, is discussed.

Amino Acid Sequence↗
PubMed1985

An adenovirus type 2 glycoprotein blocks cell surface expression of human histocompatibility class I antigens.

The adenovirus type 2 encoded protein E3/19K binds to human histocompatibility class I antigens (HLA). This association occurs both in adenovirus-infected cells and in cells that have been transfected with the gene encoding the E3/19K protein. The formation of the HLA-E3/19K complex prevents the HLA antigens from being correctly processed by inhibiting their terminal glycosylation. This effect is specific for HLA antigens and does not generally involve the glycosyltransferases. Furthermore, the HLA-E3/19K association dramatically reduces the cell surface expression of the HLA antigens. This reduced level of antigens might influence the cytotoxic T cell response. Therefore, our results show a possible molecular mechanism whereby adenoviruses, and perhaps other viruses, delay or escape the cellular immune system of the host.

Adenoviruses, Human↗
PubMed1985

Alloreactive cytolytic T-cell clones preferentially recognize conformational determinants on histocompatibility antigens: analysis with genetically engineered hybrid antigens.

Hybrid genes were constructed for the localization of allodeterminants on murine class I antigens recognized by antibodies and cytolytic T lymphocytes. By using deletion subclones of the H-2Kd and H-2Kk genes, homologous regions were exchanged between the two alleles. The altered genes were introduced and expressed in mouse fibroblast and fibrosarcoma cells. Cells expressing hybrid antigens were analyzed with 29 monoclonal anti-H-2Kd and anti-H-2Kk antibodies and with 150 short-term alloreactive cytolytic T-cell clones. When only the first or only the second amino-terminal domain was exchanged, most T cells and 60% of the antibodies lost their reactivity to the H-2K antigen. No T-cell clone was directed against the third extracellular domain, whereas three antibodies could bind to this domain. This implies that nearly all determinants essential for a cytolytic T-cell response or for antibody binding lie on the two external domains and are conformational structures generated by the interaction of these two domains.

Animals↗
PubMed1984

Complete nucleotide sequence of the murine H-2Kk gene. Comparison of three H-2K locus alleles.

We have determined the DNA sequence of the H-2Kk gene of the mouse major histocompatibility complex (MHC). Comparison on the nucleotide and protein level of three H-2K alleles (Kk, Kb and Kd) reveals a high degree of homology, in particular between the Kb and Kk alleles. Differences between the two latter antigens are almost exclusively confined to the alpha 1 and alpha 2 domains. At nine positions in the extracellular part of the molecules we have found allele-specific amino acids. Interestingly, 78% of these residues are either polar or carry hydroxyl-groups. This makes it likely that they are exposed on the surface of the molecules and might then be part of antigenic determinants. We have also identified potentially allele-specific nucleotide sequences of the K genes which might be used as specific DNA probes.

Alleles↗
PubMed1984

Cytolytic T cells recognize the two amino-terminal domains of H-2 K antigens in tandem in influenza A infected cells.

We have genetically engineered three alleles of the K locus of the major histocompatibility complex (MHC) of the mouse. These novel hybrid H-2K genes were introduced into mouse 1T 22-6 cells (H-2q), and their products were shown to be expressed on the cell surface. The hybrid H-2 K antigens were examined for their ability to function as restricting elements for cytotoxic T lymphocytes during influenza A infection. Both the alpha 1 and alpha 2 domains of the Kd antigen were required for T cell recognition. This implies an important role for "conformational determinants" on H-2 antigens acting as restricting elements. The cytoplasmic domain of the Kb antigen is not phenotypically important for recognition by T cells.

Amino Acid Sequence↗
PubMed1983

Mouse histocompatibility genes: structure and organisation of a Kd gene.

The gene coding for the mouse H-2Kd antigen has been isolated by using a K-locus specific cDNA probe. The complete nucleotide sequence of the gene reveals eight exons separated by seven introns. Transcriptionally important DNA sequences (CCAAT and TATA) precede the first exon. Comparison with other H-2 genes shows extensive homology in exons as well as in introns. Two cDNA clones encoding Kd antigens have been analysed and provide evidence for at least two expressed Kd genes in the DBA/2 mouse. Comparison of the Kd antigen sequence to three other H-2 antigens indicates that gene conversion mechanism(s) act on H-2 genes. Analyses of exon donor and acceptor sites of different H-2 genes and cDNAs show that alternative splicing sites are used by different genes.

Alternative Splicing↗
PubMed1983

The DNA sequence of the H-2kb gene: evidence for gene conversion as a mechanism for the generation of polymorphism in histocompatibilty antigens.

We have determined the DNA sequence of the H-2Kb gene of the C57B1/10 mouse. Comparison of this sequence with that of the allelic H-2Kd shows surprisingly that the exons have accumulated more mutations than their introns. Moreover, many of these changes in the exons are clustered in short regions or hot spots. Additional comparison of these sequences with the H-2Ld and H-2Db sequences shows that, in several cases, the altered sequence generated at the hot spot is identical to the corresponding region of a non-allelic H-2 gene. The clustered changes are responsible for 60% of the amino acid differences between the H-2Kb and H-2Kd genes and suggest that micro-gene conversion events occurring within the exons and involving only tens of nucleotides are an important mechanism for the generation of polymorphic differences between natural H-2 alleles.

5' Flanking Region↗
PubMed1983

Subcellular localization in normal and vitamin A-deficient rat liver of vitamin A serum transport proteins, albumin, ceruloplasmin and class I major histocompatibility antigens.

The subcellular localization in rat liver cells of retinol-binding protein (RBP), prealbumin, ceruloplasmin, albumin, and class I transplantation antigen chains was investigated by radioimmunoassay determinations. The concentration of RBP was high in the rough and smooth endoplasmic reticulum (SER). The relative concentrations of prealbumin, ceruloplasmin and albumin were similar in the endoplasmic reticulum fractions and in the Golgi fraction. Neither of the proteins were found in significant amounts in the post-microsomal supernatant nor in the plasma membrane. The concentrations of the class I transplantation antigen chains were higher in the Golgi fraction than in the endoplasmic reticulum fractions. In the rough endoplasmic reticulum (RER) fraction ceruloplasmin and the class I antigens partially interact with high-molecular weight (MW) components, presumably membrane-bound glycosyltransferases. RBP, prealbumin and albumin seemed to be present in free form within the microsomal lumen. In vitamin A deficiency the RBP and to a lesser extent the prealbumin concentrations in the endoplasmic reticulum fractions were significantly increased, as compared to fractions from normal livers. This suggests that the presence of vitamin A is a prerequisite for the transport of RBP from the endoplasmic reticulum to the Golgi complex. The intracellular concentrations of albumin and ceruloplasmin were not significantly altered by vitamin A deficiency. In contrast, the amounts of the class I antigen heavy chains were found to be increased.

Animals↗
PubMed1982

Structure and biosynthesis of histocompatibility antigens (H-2, HLA).

Histocompatibility antigens (H-2K, D and L, and HLA-A, B and C) are highly polymorphic cell surface proteins. Their primary structure has been determined by sequencing the protein, complementary DNAs (cDNAs) or genes in several laboratories. H-2Ld and Kd antigens are encoded by eight separate exons: one encodes the signal sequence, three encode the external domains, one encodes the membrane spanning segment and three encode the cytoplasmic domain. A similar structural organization has been found for an HLA gene. H-2 and HLA antigens are synthesized on membrane-bound ribosomes and are co-translationally inserted into the membrane of the endoplasmic reticulum. Here they assemble with beta 2-microglobulin, a small secretory protein. We describe the structure, the membrane insertion in vitro and in vivo, the intracellular transport and the surface expression of these antigens.

Animals↗
PubMed1982

Identification of an H-2Kd gene using a specific cDNA probe.

A cDNA clone known to code for a mouse histocompatibility (class I) antigen was found to contain a sequence specific for a subpopulation of H-2 genes. This unique sequence is located in the 3' non-coding region close to the stretch of poly(A) nucleotides. A subclone containing this fragment (pH-2d-5) has been used to select hybridizing mRNA. Translation of the mRNA in vitro shows that H-2Kd mRNA is selected. Southern blot analysis of DNA from congenic recombinant mice show that at least one gene containing this sequence is located at the K locus (region) of the major histocompatibility complex. This gene contains a 3.7-kb BglII and a 13-kb EcoRI restriction endonuclease fragment. This gene has been isolated from a genomic DNA library.

Animals↗
PubMed1982

Membrane insertion and oligomeric assembly of HLA-DR histocompatibility antigens.

HLA-DR histocompatibility antigens are assembled in the endoplasmic reticulum. This assembly has been studied in vitro and in vivo. Three polypeptides are involved in forming the oligomeric structure of HLA-DR antigens, DR alpha chains (molecular weight 35,000), DR beta chains (molecular weight 29,000) and DR gamma chains (molecular weight 33,000). They are cotranslationally inserted into the membrane of the endoplasmic reticulum, and all span the membrane. The size of the cytoplasmic portion of DR alpha and DR beta is about 500- 1000 daltons, whereas that of the DR gamma chain is about 3000 daltons. Oligomeric assembly of DR alpha, DR beta and DR gamma chains occurs shortly after their synthesis in the endoplasmic reticulum. DR gamma chains are synthesized in excess of DR alpha and DR beta chains, and hence in the endoplasmic reticulum they are found either in a complex with DR alpha and DR beta or in a free form. Free DR gamma chains remain in the endoplasmic reticulum, whereas DR gamma chains present in the oligomeric complex with DR alpha and DR beta undergo intracellular transport. Their molecular weight increases during transport, probably because of the addition of complex sugars in the Golgi complex. This is followed by the detachment of DR gamma chains from the oligomeric complex and the appearance of DR alpha and DR beta chains on the cell surface. Whether any DR gamma chains appear on the cell surface is uncertain.

Biological Transport↗
PubMed1982

Isolation and identification of a cDNA clone corresponding to an HLA-DR antigen beta chain.

The HLA-D locus in the major histocompatibility complex controls the expression of the genetically polymorphic HLA-DR antigens. mRNA coding for the beta chains of these antigens was partially purified from the human lymphoblastoid cell line Raji. The mRNA was copied into double-stranded cDNA and cloned in Escherichia coli. One clone, pDR-beta-1, obtained by hybrid selection, carries a 1070-base-pair insert comprising all of the coding region except the signal sequence and a substantial portion of the untranslated region. To identify pDR-beta-1, highly purified HLA-DR antigen beta chains derived from Raji cells were subjected to NH2-terminal amino acid sequence determination. This sequence displayed extensive homology with that deduced from the nucleotide sequence at the 5' end of the pDR-beta-1 coding region. Taken together, the amino acid and nucleotide sequences strongly argue in favor of Raji cells containing at least two beta-chain loci.

Amino Acid Sequence↗
PubMed1981

cDNA clone coding for part of a mouse H-2d major histocompatibility antigen.

mRNA coding for mouse major transplantation antigens of the d haplotype was partially purified, copied into double-stranded cDNA, and cloned in Escherichia coli. Clones were selected by their ability to hybridize specifically with mRNA coding for H-2K, D, or L antigens. One of these clones, pH-2d-1, carries a 1200-base-pair insert, comprising the noncoding region, including poly(A) at the 3' end and part of the coding region. A partial sequence of the latter region showed extensive homology with the known amino acid sequences of H-2Kb,Kk, and HLA-B7 antigens. From this comparison, it appears that the coding region extends from amino acid 133 in the second domain, through the third domain, to the cytoplasmic COOH-terminal region. A stretch of 24 hydrophobic or uncharged residues, located 31 amino acids from the COOH-terminal end, could represent the segment that spans the membrane. This is followed on the cytoplasmic side of the membrane by a cluster of basic amino acids and a possible phosphorylation site on a threonine residue.

Amino Acid Sequence↗
PubMed1980

Properties of purified papain-solubilized rat AgB antigens and reactivity of a xenoantiserum against the isolated antigens.

Rat AgB transplantation antigens were isolated after papain digestion of spleens from the inbred strain Hooded Lister. Both subunits of the AgB antigens were present in the purified material. Some physical characteristics of the antigens have been determined. An antiserum, raised in a rabbit, against the purified material reacted exclusively with AgB antigens on splenocytes but detected novel structures on both adult and embryonic fibroblasts. These structures, antigenically related to AgB antigens, were not detected on plasmacytoma or hepatoma cells, nor did they display any antigenic similarity with rat beta 2-microglobulin. Radioimmunoassays specific for the AgB antigen heavy chain and for beta 2-microglobulin, respectively, were used to estimate the contents of these antigens in several tissues. Spleen and thymus exhibit the largest density, while brain is almost devoid of these antigens.

Animals↗