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J L Strominger

Publications and source records attributed to J L Strominger.

At least 487 records · Page 27Linked to original sources
PubMed1977

Submit and disulfide structure of monomeric and dimeric forms of detergent-soluble HLA antigens.

The structure of monomeric and disulfide-bonded dimeric forms of HLA antigens has been studied. Detergent-soluble HLA antigen heavy chains contain one or two easily reduced sulfhydryl groups not found in papain-solubilized HLA antigens, as demonstrated by amino acid analysis (Springer, T. A., and Strominger, J.L. (1976) Proc. Natl. Acad. Sci. U.S.A. 73, 2481-2485, and Terhorst, C., Parham, P., Mann, D.L., and Strominger, J.L. (1976) Proc. Natl. Acad. Sci. U.S.A. 73, 910-914) and by labeling with iodo[3H]acetate. Dimer formation occurred during purification, since it was prevented by pretreatment of membranes containing HLA antigen with iodoacetamide. Cross-linking studies showed that the non-disulfide-bonded form of HLA antigens contains one subunit each of the Mr = 44,000 heavy chain and the Mr = 12,000 light chain (beta2-microglobulin).

Carbon Radioisotopes↗
PubMed1977

Kinetic evidence for an acyl-enzyme intermediate in D-alanine carboxypeptidases of Bacillus subtilis and Bacillus stearothermophilus.

The kinetics of hydrolysis and transpeptidation of the synthetic substrate diacetyl-L-lysyl-D-alanyl-D-alanine and of the natural substrate UDP-acetylmuramyl pentapeptide and related compounds catalyzed by the D-alanine carboxypeptidases of Bacillus subtilis and Bacillus stearothermophilus in the presence of the nucleophiles hydroxylamine or glycine have been examined. These kinetic data suggest that an acyl-enzyme intermediate is formed in the first step of the reaction and that the transpeptidation is the consequence of the partitioning of this intermediate between water and the nucleophile in the second step.

Alanine↗
PubMed1977

Inhibition of proliferative and plaque-forming cell responses by human bone-marrow-derived lymphocytes from peripheral blood by antisera to the p23, 30 antigen.

A recently described technique for the polyclonal induction of plaque-forming cells from human bone-marrow derived (B) lymphocytes of peripheral blood has been used to assess the role of a human Ia-like antigen (p23,30) in differentiation of human B cells. In particular, the effects of antisera to p23,30 on the plaque-forming cells and proliferative responses of human B cells stimulated by pokeweed mitogen or soluble products of activated human thymus-derived lymphocytes (T cells) have been examined. Antisera to p23,30 eliminated the development of plaque-forming cells induced by both T cell products and pokeweed mitogen. While these antisera also abrogated B cell proliferation induced by T cell supernatants, the proliferative response generated by pokeweed mitogen was only partially reduced. It was also determined that while the p23,30 antigen continues to be expressed on fully differentiated plaque-forming cells, antisera to this determinant exert inhibitory effects on B cell differentiation only when present during the early stages of B cell cultures. These results lend further support to the analogy between p23,30 and murine Ia antigens. Moreover, they demonstrate a major role for this antigen in the early events involved in human B cell differentiation into antibody-forming cells.

Antigen-Antibody Reactions↗
PubMed1977

Isolation of the penicillin-binding peptide from D-alanine carboxypeptidase of Bacillus subtilis.

The D-alanine carboxypeptidase of B. subtilis is a membrane-bound enzyme which is inhibited by penicillins and binds them covalently. The enzyme has been labeled with [14C]- or [35S]penicillin. After tryptic or Pronase digestion of the labeled, denatured, reduced, and carboxymethylated enzyme, a radioactive peptide was isolated in each case. The amino acid compositions of these two peptides are reported. The Pronase peptide was a subset of the tryptic peptide. Neither contained a cysteine residue and the only amino acid in the Pronase peptide to which the penicillin could be bound was a serine residue.

Alanine↗
PubMed1977

Simultaneous deletion of D-alanine carboxypeptidase IB-C and penicillin-binding component IV in a mutant of Escherichia coli K12.

Mutants of Escherichia coli with much decreased activity of D-alanine carboxypeptidase (peptidyl-D alanine hydrolase, EC 3.4.12.11) were found among E. coli K12 extensively mutagenized with nitrosoguanidine treatment by assaying individual colonies for the enzyme activity. One such mutant with only 10-12% residual activity was characterized extensively. The soluble carboxypeptidase activity (corresponding to D-alanine carboxypeptidase IC of Tamura T., Imae, Y. & Strominger, J.L. [(1976) J. Biol. Chem. 251, 414-423] was deleted. This enzyme activity in the particulate fraction was markedly reduced but transpeptidase activity was normal. However, penicillin-binding component IV was deleted from the particulate fraction. Both the physiology and penicillin sensitivity of the organism were relatively normal, except that mutant cells were markedly more stable to penicillin-induced lysis, suggesting the possibility that carboxypeptidase IC really functions as an endopeptidase. The possible relationship of the deleted carboxypeptidase activity and the deleted penicillin binding component are discussed.

Ampicillin↗
PubMed1977

HLA-D associated alloantisera react with molecules similar to Ia antigens.

Two human alloantisera specific to bone marrow-derived lymphocytes (B cells) were shown to precipitate polypeptide chains of 29,000 and 34,000 daltons from human lymphoblastoid B cell lines. These molecules are similar to murine Ia antigens and are also precipitated by a rabbit B-cell specific heteroantiserum. Since the alloantisera are thought to recognize determinants coded by HLA-D or closely linked loci, these data support the hypothesis that these B-cell specific alloantigens are the human counterpart of the mouse Ia antigens and may be the products of HLA-D.

B-Lymphocytes↗
PubMed1977

Further structural studies of the heavy chain of HLA antigens and its similarity to immunoglobulins.

The papain-solubilized fragment of the heavy chain of HLA-B7, which is the NH2-terminal part of the whole polypeptide chain, can be divided into three regions by mild acid and cyanogen bromide cleavages. The first 100 amino acids terminating in a methionine residue contain the carbohydrate moiety; this segment is followed by two others of molecular weights 9,999 and 13,000, each containing an intrachain disulfide bridge. The two intrachain disulfide bridges are separated by a stretch of amino acids containing an acid-labile aspartyl-prolHLA-2, A28, and AW25 contain this acid-labile peptide bond in their larger subunit. Sequencing from the acid cleavage site of HLA-7 through the third half-cystine revealed consideralbe homology with amino acid sequences around a half-cystine in immunoglobulin variable regions.

Amino Acid Sequence↗
PubMed1977

Structure of HL-A A and B antigens isolated from cultured human lymphocytes.

From these data, a model was prepared which summarizes schematically our present knowledge of the structure and orientation of the HL-A antigenic molecule in the lymphocyte membrane (Fig. 3). It seems likely that the heavy chain spans the membrane, with the hydrophobic region inserted in the membrane and the hydrophilic C-terminus inside the cell. This C-terminal region bears one (possible two) SH residue which has the potential for forming interchain disulfides. Whether or not these are actually formed physiologically remains an interesting question. There is the attractive possibility that whatever the physiological functions of HL-A antigens are, structurally these molecules provide the potential for signaling from outside the cell to inside the cell because they span the membrane. It is even conceivable that this function might be expressed via the opening and closing of disulfide bridges.

Amino Acid Sequence↗
PubMed1977

The shape-maintaining component of halobacterium salinarium: a cell surface glycoprotein.

Halobacterium salinarium lacks the rigid peptidogylcan layer necessary for shape-maintenance in most bacteria. Instead, the major cell surface component is a high-molecular-weight glycoprotein resembling those found on the surface of eukaryotic cells. The glycoprotein is extremely acidic and has carbohydrate units attached via both N- and O-glycosidis linkages. Evidence has been obtained that demonstrates that the glycoprotein forms a rigid structural matrix at the cell surface and is responsible for maintenance of the characteristic rod-shaped morphology of these organisms.

Bacitracin↗
PubMed1976

Formation of lipid-linked sugar compounds in Halobacterium salinarium. Presumed intermediates in glycoprotein synthesis.

The ability of bacitracin to inhibit the growth of Halobacterium salinarium suggested that glycosylation of the major envelope component, a high molecular weight glycoprotein, might occur via a pathway involving lipid intermediates. This report demonstrates that the cells have enzymatic activities for formation of lipid-linked sugar compounds having the expected properties of such intermediates. Whole cell homogenate catalyzed the transfer of sugar from UDP-glucose, GDP-mannose, and UDP-N-acetyglucosamine to endogenous lipid acceptors. Two lipid products were formed from UDP-glucose, two from GDP-mannose, and one from UDP-N-acetylglucosamine. Characterization of the partially purified lipids by ion exchange chromatography, thin layer chromatography, and mild acid and base hydrolysis showed the major product in each case to have the properties expected for polyisoprenyl phosphoglucose, polyisoprenyl phosphomannose, and polyisoprenyl pyrophospho-N-acetylglucosamine. Estimates of chain length by thin layer chromatography indicate that the lipid has 11 to 12 isoprene identity as a C55-60-polyisoprenyl pyrophospho-N-acetylglucosamine. The N-acetylglucosamine transferase, present in cell envelope preparations, was partially characterized. The enzyme was found to be extremely halophilic, specifically requiring a high concentration of KCl. Optimum activity was obtained at 4 m KCl and partial substitution of K+ by Na+ resulted in a decrease in activity.

Cell Membrane↗