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D Larhammar

Publications and source records attributed to D Larhammar.

122 records · Page 7Linked to original sources
PubMed1983

The complete nucleotide sequence of the I-E alpha d immune response gene.

We have isolated and sequenced the complete murine I-E alpha immune response gene of the H-2db haplotype. The I-E alpha d gene consists of 5300 basepairs and is organized into five or possibly six exons that correspond to different domains of the alpha chain. The amino acid sequence deduced from the I-E alpha gene shows 75% homology to its human counterpart, the HLA-DR alpha chain. The absence of I-E antigen in H-2 mice is due to lack of E alpha chain synthesis. We show here that this defect is caused by a deletion in the 5' end of the I-E alpha b gene.

Amino Acid Sequence↗
PubMed1983

Structure of the murine immune response I-A beta locus: sequence of the I-A beta gene and an adjacent beta-chain second domain exon.

The murine major histocompatibility complex I region encodes two class II antigens, I-A and I-E. From a mouse spleen DNA cosmid library of the b haplotype, we isolated a clone containing the entire I-A beta gene and a separate exon encoding a beta-chain second domain (A beta 2). The A beta gene, encompassing more than 6 kb, is encoded by six exons corresponding to the different domains of the A beta polypeptide. The translated A beta amino acid sequence displays 73% homology to human DC beta chains; homologies to other subsets of human beta chains are lower, establishing that I-A corresponds structurally to DC. The A beta 2 exon is about 20 kb centromeric to the A beta gene. Its translated amino acid sequence includes all the conserved amino acids of other class II beta-chain second domains. It shows about 60% homology to each of three subsets of human beta chains available for comparison, and to the A beta chain. No A beta 2 first domain exon has been detected with A beta or DC beta probes.

Amino Acid Sequence↗
PubMed1983

Exon-intron organization and complete nucleotide sequence of a human major histocompatibility antigen DC beta gene.

We have determined the complete nucleotide sequence of a human class II histocompatibility antigen DC beta gene. The gene spans more than 7 kilobases and contains five exons corresponding to the different domains of the DC beta polypeptide. The exon-intron organization is thus analogous to that of class II antigen alpha-chain genes, class I antigen heavy chain genes, and the constant parts of immunoglobulin genes, emphasizing further the evolutionary relationship among these molecules. The mature polypeptide deduced from the DC beta gene shows 93% and 88% homology, respectively, to sequences derived from two DC beta cDNA clones of other haplotypes. The allelic polymorphism of DC beta chains resides predominantly in the first extracellular domain, whereas the rest of the polypeptide is virtually constant. The exons of the DC beta gene display high homology to the corresponding exons of a murine I-A beta gene. Also, the introns show significant homology. The DC beta chains lack eight amino acids in the cytoplasmic tail, as compared to DR and I-A beta chains. This is probably due to a nonfunctional splice junction of DC beta genes, causing a separate cytoplasmic exon to be nonexpressed.

Amino Acid Sequence↗
PubMed1983

cDNA clone for the human invariant gamma chain of class II histocompatibility antigens and its implications for the protein structure.

The invariant gamma chain is transitorily associated with class II histocompatibility antigens during intracellular transport. We have isolated and sequenced a cDNA clone corresponding to the human gamma chain. mRNA hybridizing to the cDNA clone translated into a 33,000-dalton chain that associated specifically with class II antigen alpha and beta chains. The gamma chain consists of 216 amino acids. The two N-linked carbohydrates are attached to asparagines 114 and 120. A continuous stretch of hydrophobic and neutral amino acids occurs in positions 31-56 from the NH2 terminus. This region seems to constitute the transmembrane portion of the polypeptide chain. The positions of the carbohydrate moieties and the putative transmembrane segment indicate that the NH2 terminus of the gamma chain resides on the cytoplasmic side of the membrane. Cell-free translations in conjunction with radiochemical amino acid sequence analyses suggest that the gamma chain lacks an NH2-terminal signal sequence.

Amino Acid Sequence↗
PubMed1982

Alpha chain of HLA-DR transplantation antigens is a member of the same protein superfamily as the immunoglobulins.

Four cDNA clones, pDR-alpha-1, pDR-alpha-2, pDR-alpha-3 and pDR-alpha-4, corresponding to the alpha chain of HLA-DR antigens, have been sequenced. Restriction maps and sequences suggest that all clones are identical apart from a single-base substitution present in pDR-alpha-1. Amino acid sequence data, together with the nucleotide sequence data, allowed the complete amino acid sequence to be predicted. The alpha chain is composed of 229 amino acids, of which 191 are exposed on the outside of the plasma membrane. The membrane-embedded portion of the chain consists of 23 hydrophobic amino acids. The succeeding 15 amino acids form the cytoplasmically localized hydrophilic tail. The extracellular portion, with carbohydrate moieties linked to Asn78 and Asn118, seems to be organized into two domains. The second domain, which contains the only disulfide bond of the alpha chain, displays amino acid sequence homology to immunoglobulin constant regions, to the second domain of the beta chain of a class II antigen, to the third domain of heavy chains of class I antigens and to beta 2-microglobulin. Thus the subunits of immunoglobulins, class I antigens and class II antigens are related evolutionarily.

Amino Acid Sequence↗
PubMed1982

Complete amino acid sequence of an HLA-DR antigen-like beta chain as predicted from the nucleotide sequence: similarities with immunoglobulins and HLA-A, -B, and -C antigens.

The complete nucleotide sequence of an HLA-DR antigen-like beta-chain cDNA clone was determined. The 1,080 base pairs include the complete coding region and most of the untranslated portion. The predicted amino acid sequence has 229 residues. The beta chain contains two immunoglobulin-like disulfide loops and a 21-amino acid residue membrane-integrated segment. Ten amino acid residues reside on the cytoplasmic side of the plasma membrane. The single asparagine-linked carbohydrate moiety is attached to asparagine-19. The NH2-terminal 91 residues of the beta chain are homologous to the corresponding region of HLA-A, -B, and -C antigen heavy chains. Residues 92-192 of the beta chain display statistically significant homology to members of the immunoglobulin family, beta 2-microglobulin, and the immunoglobulin-like domain of HLA-A, -B, and -C antigen heavy chains. These data establish that the major histocompatibility antigens of class I and class II type and the constant regions of immunoglobulins are evolutionarily related.

Amino Acid Sequence↗
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↗
PubMed1982

Isolation and identification of a cDNA clone coding for an HLA-DR transplantation antigen alpha-chain.

Membrane-bound mRNA was isolated from Raji cells and enriched for message coding for the HLA-DR transplantation antigen alpha-chain by sucrose gradient centrifugation. Double-stranded cDNA was constructed from this mRNA fraction, ligated to plasmid pBR322, and cloned into Escherichia coli. By hybrid selection, a plasmid, pDR-alpha-1, able to hybridize with mRNA coding for the HLA-DR alpha-chain was identified. From the nucleotide sequence of one end of the insert an amino acid sequence was predicted which is identical to part of the amino-terminal sequence of an HLA-DR alpha-chain preparation isolated from Raji cells. This clearly shows that pDR-alpha-1 carries almost the complete message for an HLD-DR alpha-chain. From the nucleotide sequence of this plasmid it will be possible to predict the primary structure of an HLA-DR alpha-chain.

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↗
PubMed1981

Evolutionary relationship between HLA-DR antigen beta-chains, HLA-A, B, C antigen subunits and immunoglobulin chains.

cDNA for a beta-chain of HLA-DR antigens was cloned and the partial nucleotide sequence was determined. The data suggest that the beta-chain consists of approximately 230 amino acids, of which about 200 are exposed on the cell surface. The beta-chain appears to be composed of two exposed disulphide-containing domains. The arrangement of the disulphide loops suggests that the beta-chain is similar in structure to the HLA-A, B, C antigen subunits and the immunoglobulin chains. For the beta-chain domain closest to the membrane this similarity was verified at the level of primary structure. The partial amino acid sequence of the NH2-terminal domain did not display any apparent homology to HLA-A, B, C antigens and immunoglobulins. However, the similarity established here between the two types of major histocompatibility antigen subunits and the immunoglobulin chains suggests a common ancestral origin for at least some regions of these molecules.

Base Sequence↗
PubMedDate not supplied

Binding of chimeric NPY/galanin peptides M32 and M242 to cloned neuropeptide Y receptor subtypes Y1, Y2, Y4, and Y5.

Ligand binding to neuropeptide Y (NPY) receptors Y1, Y2, Y4, and Y5 from guinea-pig was investigated using the two NPY-galanin hybrids M32 (galanin1-13-NPY25-36-amide) and M242 ([D-Trp(32)]M32). The affinity of M32 for Y1, Y2, and Y4 receptors was 13, 4, and 30nM, respectively, similar to that of NPY18-36 and NPY22-36 but 40-fold to 300-fold lower than the affinity of intact porcine NPY. M242 bound to the Y1, Y2, and Y4 receptors with 9-fold to 20-fold lower affinity than did M32. The affinities of M32 and M242 for Y5 were 400 and 800 nM, respectively. Thus, M32 seems to gain affinity relative to both of its constituent peptide portions although the NPY25-36 part may be sufficient for NPY-receptor recognition, especially at the Y2 receptor. This suggests that the galanin portion of M32 influences and/or stabilizes the conformation of the NPY portion, similar to the effect seen for the NPY portion of M32 in binding to galanin receptors.

Amino Acid Sequence↗
PubMedDate not supplied

Mutagenesis of the human 5-HT1B receptor: differences from the closely related 5-HT1A receptor and the role of residue F331 in signal transduction.

We have used a combination of sequence comparisons, computer-based modeling and site-directed mutagenesis to investigate the molecular interactions involved in ligand binding and signal transduction of the human 5-HT1B receptor. Two amino acid residues, S212 in transmembrane region (TM) V and F331 in TM VI, were replaced by alanines. These amino acids are conserved in many G protein-coupled receptors and therefore likely to be important for receptor function. The mutant receptors were expressed in Chinese hamster ovary cells. The 5-HT-like agonist 5-carboxamido-tryptamine (5-CT) bound with 15-fold lower affinity to the S212A mutant as compared to wild-type receptor and the antagonist methiothepin bound with 17-fold lower affinity to the F331A mutant. No reduction in the affinity of 5-HT was seen for the S212A mutant, although an equivalent mutation in the 5-HT1A receptor resulted in a 100-fold reduction of 5-HT binding. The inhibition of forskolin-stimulated cyclic AMP production by 5-HT was significantly reduced in cells expressing the F331A mutant, even though the endogenous ligand 5-HT bound with somewhat increased affinity. Methiothepin acted as an inverse agonist and increased the forskolin-stimulated cyclic AMP production at both the wild-type receptor and the mutants, and the effect was stronger on the F331A mutant. These results suggest that F331 is involved in the conformational changes necessary for signal transduction.

Animals↗