Important note: Information in this article was accurate in 1994. The state of the art may have changed since the publication date.
C33 antigen and M38 antigen recognized by monoclonal antibodies inhibitory to syncytium formation by human T cell leukemia virus type 1 are both members of the transmembrane 4 superfamily and associate with each other and with CD4 or CD8 in T cells.
J Immunol. 1993 Dec 1;151(11):6470-81. Unique Identifier : AIDSLINE MED/94065201 Imai T; Yoshie O; Shionogi Institute for Medical Science, Osaka, Japan.
Abstract:
C33 Ag and M38 Ag had been identified by mAb inhibitory to HTLV-1-induced syncytium formation. The cDNA encoding C33 Ag had revealed that it belongs to the newly defined transmembrane 4 superfamily (TM4SF). M38 Ag was detected on virtually all human cell lines and fresh leukocytes except for most granulocytes. It was also expressed on a mouse hybrid cell clone containing human chromosome 11q23-pter. Immunoprecipitation and immunoblot analyses identified a monomeric 26-kDa protein. The M38 epitope was dependent on S-S bonding. These characteristics were very similar to those reported for TAPA-1 (the target of antiproliferative antibody-1), which also belongs to TM4SF as C33 Ag. We therefore cloned the cDNA of human TAPA-1 and expressed it in COS cells. M38 indeed reacted with COS cells expressing human TAPA-1. We concluded that M38 Ag was identical to TAPA-1. To further investigate the biologic functions of C33 Ag and M38 Ag (TAPA-1) and their roles in HTLV-1-induced syncytium formation, molecules associated with these Ag were examined in T cells. Immunoprecipitation from surface-iodinated cell lysates revealed that proteins co-precipitated by C33 and M38 were mostly common including each other. Sequential immunoprecipitation-immunoblot experiments confirmed that C33 Ag and M38 Ag (TAPA-1) were associated with each other. The association was further confirmed in BHK cells doubly transfected with human cDNA for C33 Ag and TAPA-1. We extended similar analyses and found that C33 Ag and M38 Ag (TAPA-1) were regularly associated with CD4 or CD8. The association of these Ag on the cell surface was further supported by co-modulation of M38 Ag (TAPA-1), CD4 and CD8 with C33 Ag. This is the first time that a physical association between the members of TM4SF is demonstrated. Furthermore, the regular association of C33 Ag and M38 Ag (TAPA-1) with CD4 or CD8 might indicate that they play a role in expression and/or function of the CD4/CD8 co-receptor complex.
Keywords: Antibodies, Monoclonal/*IMMUNOLOGY Antigens, CD4/*ANALYSIS Antigens, CD8/*ANALYSIS Antigens, Surface/*ANALYSIS Base Sequence Cell Line Cells, Cultured Cholic Acids/PHARMACOLOGY Human HTLV-I/*IMMUNOLOGY Membrane Proteins/*ANALYSIS Molecular Sequence Data T-Lymphocytes/*IMMUNOLOGY Transfection JOURNAL ARTICLE 940330
M9430882
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Important note: Information in this article was accurate in 1994. The state of the art may have changed since the publication date.
