Biomedical subjects

M Zacheis

Publications and source records attributed to M Zacheis.

5 recordsLinked to original sources

PubMed1993

Polymorphism in the promoter region of HLA-DRB genes.

Polymorphism is a hallmark of the molecules encoded within the MHC of humans and other mammals. Recently, evidence of polymorphism has also been shown to exist in the transcriptional regulatory regions of HLA-DQB genes. In this article, we report that polymorphism exists also in the promoter region of HLA-DRB genes. The sequence of the regulatory region of DRB genes from five homozygous DR B-cell lines, each of a distinct DR haplotype, revealed a number of differences, some of which are in the critical class II boxes that are generally conserved in class II promoters. The major differences occurred in a comparison of DR4 to the other DR haplotypes. These data suggest the existence of another important source of HLA class II polymorphism that may play a role in susceptibility to HLA-associated autoimmune disease.

Base Sequence↗

PubMed1988

Human Ia alpha- and beta-chains are sulfated.

The human Ia antigens (DR, DQ, and DP), determined by genes with the HLA complex, are heterodimers consisting of a 34,000-Da alpha-chain glycoprotein and a 29,000-Da beta-chain glycoprotein. During the course of studies characterizing a recently described sulfated proteoglycan that is specifically associated with Ia, we discovered that there were also nonproteoglycan sulfated components present in the Ia immunoprecipitates. One-dimensional sodium dodecyl sulfate-gel analysis of these latter sulfated components derived from both DR and DQ immunoprecipitates indicated that these components have mobilities indistinguishable from conventional Ia alpha and beta glycoproteins. Two-dimensional gel analysis confirmed these findings and revealed that Ia-associated invariant proteins are sulfated as well. The sulfate moiety was not removed by endoglycosidase F treatment, suggesting that the protein portion of the molecule was sulfated. These results indicate that Ia alpha-, beta-, and invariant chains can be sulfated and raise the possibility that sulfation may play a role in the physiology of Ia molecules.

Cell Line↗

PubMed1988

Characterization of the cDNA encoding a protein binding to the major histocompatibility complex class II Y box.

The expression of HLA class II genes is regulated by a series of cis-acting elements and trans-acting factors. Several cis-acting elements have been identified and have been termed the Z box, X box, Y box, octamer, and "TATA" box. The Y box contains an inverted CCAAT box. By probing a phage lambda gt11 library with double-stranded oligonucleotides, we have directly isolated a cDNA encoding a Y box-binding protein designated YB-1. YB-1 binding has an absolute requirement for the CCAAT box and relative specificity for the Y box. It has a Mr of 35,414, contains 18% basic residues, and contains putative nuclear localization signals. An inverse correlation of YB-1 and HLA-DR beta chain mRNA levels suggests that YB-1 is a negative regulatory factor.

Amino Acid Sequence↗

PubMed1986

Analysis of normal human tonsil class II antigen glycosylation by lectin affinity chromatography.

Human class II molecules include the HLA-DR, -DQ, and -DP alloantigens. Each class II molecule consists of two glycosylated polypeptide chains, the alpha chain and the beta chain. We have used lectin affinity analysis to investigate the glycosylation pattern of [3H]mannose-labeled glycopeptides derived from isolated alpha and beta chains of HLA-DR and -DQ molecules of normal tonsil cells. Glycopeptides obtained by Pronase digestion of each isolated chain were passed sequentially over columns of immobilized concanavalin A, Lens culinaris lectin, and phytohemagglutinins E and L in a prescribed manner to generate a lectin affinity profile which could be used to assign a minimal oligosaccharide structure for each glycopeptide studied. The data presented here demonstrate that a given class II polypeptide chain can bear several different oligosaccharides. Comparison of the glycosylation patterns of the HLA-DR and -DQ molecules shows that they are similar in most respects. However, there are qualitative differences in the oligosaccharides borne by HLA-DQ and -DR molecules. In addition, comparison between HLA-DQ and the homologous murine I-A molecules shows species-specific glycosylation patterns.

Antibodies, Monoclonal↗

PubMed1986

A new polymorphic determinant on HLA-DQ molecules.

In man, the immune response genes are located within the HLA-D/DR region, and the gene products, the Ia antigens, are expressed on B lymphocytes, monocytes, and a percentage of null cells and activated T lymphocytes. We recently identified a human Ia antigen, K19, which appeared to be limited in its expression to B lymphocytes, and to be preferentially expressed on the more mature cells within this population. This work was facilitated by a monoclonal antibody. HK-19, which recognized a monomorphic determinant of this Ia molecule. We now report the characterization of a second monoclonal antibody, HK-13, which recognized the same molecule as HK-19, but only on cells from some individuals. The greater affinity of HK-13 allowed more complete characterization of the K19/K13 molecule. This characterization included cytofluorography, two-dimensional gel electrophoresis, tryptic peptide mapping, and partial N-terminal amino acid sequencing, and indicated that K19 and K13 were epitopes on HLA-DQ (DC) molecules. The pattern of reactivity of HK-13 on a panel of typing cells did not correlate with any of the known HLA-DQ polymorphic determinants. Thus, HK-13 is a new polymorphic determinant of the HLA-DQ series.

Amino Acid Sequence↗