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K Wiman

Publications and source records attributed to K Wiman.

27 records · Page 2Linked to original sources
PubMed1979

Fragmentation of the human transplantation antigen heavy chain by limited proteolysis, acid cleavage, and cyanogen bromide treatment.

Highly purified, papain-solubilized HLA-A, -B, and -C antigens comprising a mixture of a great number of allelic forms from at least three loci have been fragmented by limited proteolysis, acid cleavage, and cyanogen bromide treatment. Limited proteolysis of 125I-labeled HLA-A, -B, and -C antigens with trypsin, chymotrypsin, thermolysin, and pepsin resulted in the production of two large fragments. One fragment was associated with beta 2-microglobulin and contained all of the carbohydrate. The other fragment, which had a molecular weight of about 13,000, is most probably derived from the COOH-terminal part of the heavy chain. Acid cleavage of the HLA antigen heavy chain gave rise to two main fragments with molecular weights of 22,000 and 11,000. Both fragments contained disulfide bonds. Two minor components, representing further cleavage products of the 22,000-dalton fragment, were also observed. Cleavage of the HLA antigen heavy chain at methionyl residues gave rise to one carbohydrate-containing, cysteine-free 14,000-dalton fragment and one 20,000-dalton fragment that contained all cysteines but no carbohydrate. NH2-terminal amino acid sequence analyses demonstrated that the 22,000-dalton acid cleavage fragment and the 14,000-dalton cyanogen bromide fragment were derived from the NH2-terminal part of the HLA antigen heavy chain.

Amino Acid Sequence↗
PubMed1979

Demonstration of HLA-DR-like antigens on milk fat globule membranes.

Milk fat globules (MFG), which are formed by exocytosis of lipid from epithelial cells of the mammary gland, are enveloped by plasma membrane from the epithelial cells. Highly purified, detergent-solubilized MFG membranes have been shown to contain molecules reactive with a rabbit antiserum against HLA-DR antigens. Indirect immunoprecipitation combined with polyacrylamide gel electrophoresis in sodium dodecyl sulfate demonstrated that the MFG membrane material reactive with the antiserum comprised molecules which under denaturing conditions displayed molecular weights of 28,000 and 35,000. The two types of polypeptide chains, which were both glycosylated, were held together by noncovalent forces under nondenaturing conditions. Various types of chemical and physicochemical analyses failed to reveal any significant differences between the HLA-DR-like antigens from MFG and from spleen cells. Since the HLA-DR-like antigens bound detergent in micellar form and were expressed on the outside of intact MFG, as revealed by indirect immunofluorescence, it is concluded that these antigens are embedded in the hydrocarbon matrix of the MFG and not merely passively adsorbed onto the MFG.

Antigens, Surface↗
PubMed1979

Amino acid sequence of an immunoglobulin-like HLA antigen heavy chain domain.

The classical human transplantation antigens, derived from the HLA-A, -B, and -C loci, are cell-surface-expressed glycoproteins. On the exterior of the cell the transplantation antigen heavy chain exposes two disulfide-containing domains and a glycosylated NH2-terminal extension. The disulfide-containing domain closest to the membrane has been isolated and its amino acid sequence has been determined. The HLA antigens used for the sequence analysis were derived from two and possibly three loci and comprised several allelic forms. The primary structure was remarkably invariant, and amino acid variations were observed only at three positions. Whether this suggests that the allelic variation of the HLA antigens is preferentially confined to other regions of the molecule or is a result of fortuitous selection of peptides remains to be established. The sequenced portion of the HLA antigen heavy chain is as homologous to beta 2-microglobulin and immunoglobulin light and heavy chains as are the latter to one another. This observation strengthens the notion that the transplantation antigens and the immunoglobulins are evolutionarily related.

Amino Acid Sequence↗
PubMed1979

Primary structure of pooled, papain-solubilized HLA-A, -B, and -C antigens.

The tentative amino acid sequence of pooled, papain-solubilized HLA antigen heavy chains has been determined. The amino acid sequence comprises 273 residues. As the structural analyses were performed on HLA antigen heavy chains comprising a mixture of several allelic forms derived from the A, B, and possibly C loci, multiple residues were encountered in several positions. However, a quantitatively dominating residue could always be easily identified. The present data suggest that the amino acid variability of the HLA-A, -B, and -C antigens is found in restricted regions of the molecule. The COOH-terminal third of the HLA antigen heavy chain appears to be less variable than other regions of the molecule. Previous work has shown that the HLA antigen heavy chain contains two immunoglobulin-like disulphide loops. The COOH-terminal third of the heavy chain was shown to be similar in primary structure to beta 2-microglobulin and the immunoglobulin G constant domains.

Amino Acid Sequence↗
PubMed1978

Amino acid sequence homology between HLA-A,B,C antigens, beta2-microglobulin and immunoglobulins.

Papain-solubilized HLA-A,B,C antigen heavy chains have been cleaved by combined acid and CNBr treatment to yield three large fragments. A 14,000-dalton peptide comprises the NH2-terminal portion of the molecule, less a five-membered peptide. The 14,000-dalton fragment is followed in the linear sequence by a 9000-dalton peptide connected through an aspartyl-prolyl bond to the COOH-terminal 11,000-dalton fragment. The 9000- and 11,000-dalton fragments contain disulphide bridges that are immunoglobulin-like inasmuch as they encompass some fifty-five to sixty amino acid residues. The NH2-terminal portion of the HLA antigen heavy chain is devoid of cysteine. NH2-terminal amino acid sequence analyses do not reveal homologies between the 14,000- and 9000-dalton fragments, beta2-microglobulin, and the constant immunoglobulin domains. However, the NH2-terminal sequence of the 11,000-dalton fragment is as homologous to beta2-microglobulin and the constant immunoglobulin domains as they are to one another.

Amino Acid Sequence↗
PubMed1978

Cell surface antigens containing beta2-microglobulin as the common subunit.

beta2-Microglobulin, which was first discovered in various biological fluids, has been shown to be the common subunit of the human HLA-A,B,C antigens. In the mouse beta2-microglobulin is associated with H-2K, D and L antigens and with TL and Qa-2 antigens, beta2-microglobulin and the heavy HLA antigen chains are similar in structure to the immunoglobulins and it is suggested that the two types of molecules have had an interrelated evolution. Data are also presented which suggest that the structural similarity between transplantation antigens and immunoglobulins may be paralleled by a functional similarity as well.

Animals↗