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L Rask

Publications and source records attributed to L Rask.

At least 163 records · Page 9Linked to original sources
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

Role of beta2-microglobulin in the intracellular processing of HLA antigens.

The biosynthesis of HLA-A, -B, and -C antigens was examined in the two lymphoblastoid cell lines DAUDI and RAJI. In RAJI cells the HLA-A, -B, and -C antigen heavy chains become core-glycosylated in the endoplasmic reticulum as evidenced by their sensitivity to endo-H digestion and tunicamycin treatment. Beta2-Microglobulin is present in excess in the endoplasmic reticulum of the RAJI cells and associates with the heavy chain at the time of synthesis of the heavy chain. Pulse-chase experiments demonstrated that the RAJI HLA-A, -B, and -C antigen heavy chains become terminally glycosylated since their changed characteristics included resistance to endo-H digestion, sensitivity to neuraminidase treatment, and incorporation fucose. DAUDI HLA-A, -B, and -C antigen heavy chains are synthesized normally and become core-glycosylated but not terminally glycosylated. Other glycosylated cell surface proteins, like the HLA-DR antigens, display normal glycosylation in DAUDI cells. Therefore it is unlikely that the absence of terminally glycosylated HLA-A, -B, and -C antigen heavy chains is the result of a general defect in the biosynthetic machinery of DAUDI cells. However, DAUDI cells lack the ability to synthesize beta2-microglobulin, the common subunit of all HLA-A, -B, and -C antigens. Therefore, it seems reasonable to conclude that beta2-microglobulin is of importance for intracellular transport of newly synthesized HLA-A, -B, and -C antigens.

Beta-Globulins↗
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↗
PubMed1980

On the stoichiometry of the interaction between prealbumin and retinol-binding protein.

The stoichiometry of the interaction between prealbumin and retinol-binding protein was investigated. Gel chromatography analyses of prealbumin on columns equilibrated with retinol-binding protein (RBP)-containing buffers and fluorescence polarization analyses of RBP in the presence of various concentrations of prealbumin demonstrated that 3 molecules of RBP could simultaneously bind to prealbumin. Each RBP molecule seemed to interact with prealbumin with an apparent association constant of about 7.8 X 10(6) M-1. Fab fragments of anti-iudiotypic antibodies raised against anti-RBP antibodies reaced specifically with the RBP-binding sites on prealbumin. Two anti-idiotypic Fab fragments could simultaneously interact with prealbumin. These data strongly suggest that prealbumin exhibits at least two RBP-binding sites.

Binding Sites↗
PubMed1980

Complete amino acid sequence of pooled papain-solubilized HLA-A, -B, and -C antigens: relatedness to immunoglobulins and internal homologies.

Pooled, papain-solubilized HLA-A, -B, and -C antigens, derived from a large number of individuals and comprising several allelic forms, have been subjected to amino acid sequence determination. Despite the heterogeneity of the material, a main sequence representing all of the 273 amino acid residues could be established. The primary structure encompasses two immunoglobulin-like disulfide loops. The single carbohydrate moiety is attached to asparagine-86. Computer analyses demonstrated that the COOH-terminal one-third of the sequence, called H3, display statistically significant homology with members of the immunoglobulin family. The NH2-terminal two-thirds of the molecule, called H1 and H2, are not significantly homologous to any of the immunoglobulin sequences. However, H1 and H2 exhibit a distant relatedness to each other but no obvious similarity to the H3 region.

Amino Acid Sequence↗
PubMed1980

The retinol-binding protein.

Vitamin A is transported from its storage site in the liver to the epithelial tissues by a carrier protein, the Retinol-binding protein (RBP). In plasma RBP forms a complex with thyroxine-binding prealbumin. The present article reviews available data on the RBP system. The complete primary structure of RBP has been determined. The plasma concentration of RBP is regulated by the vitamin A status so that in vitamin A deficiency RBP molecules are not secreted from the liver. RBP molecules interact with a cell membrane receptor, probably a protein component present on epithelial cells. Vitamin A is thereby delivered to the cells. The uptake of vitamin A by the cells causes a reduction of the affinity of RBP for prealbumin. The RBP molecules which no longer are able to interact efficiently with prealbumin are excreted through the kidney glomerulus and degraded.

Amino Acid Sequence↗