Processing and major histocompatibility complex binding of the MTV7 superantigen.
Mouse mammary tumor viruses produce superantigens (vSAGs) which interact with class II major histocompatibility complex (MHC) proteins and stimulate T cells. vSAGs are synthesized as Type II membrane proteins, but at least one of these proteins (vSAG7) is found on the cell surface in a proteolytically processed form. Monoclonal antibodies (MAbs) were used to characterize vSAG7 and its binding to class II molecules. vSAG7 is synthesized in the endoplasmic reticulum (ER) as a 45 kd glycoprotein containing N-asparagine-linked oligomannosyl carbohydrates. vSAG7 transits the golgi complex, where it is modified by the addition of complex-type glycans and proteolysed at three positions. After proteolysis, the amino and carboxyl termini remain noncovalently associated. The ER, golgi, and surface forms of vSAG7 are stably bound to class II, but one of the proteolysed forms comprises the majority of the class II-bound material.
Winslow
G M
GM
Howard Hughes Medical Institute, Department of Medicine, National Jewish Center for Immunology and Respiratory Medicine, Denver, Colorado 80206.
Marrack
P
P
Kappler
J W
JW
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D017951:Antigen Presentation; D001693:Biological Transport, Active; D002460:Cell Line; D002462:Cell Membrane / Q000276:immunology / Q000378:metabolism / Q000821:virology; D006224:Cricetinae; D010450:Endopeptidases / Q000378:metabolism; D006031:Glycosylation; D006056:Golgi Apparatus / Q000276:immunology / Q000378:metabolism; D000949:Histocompatibility Antigens Class II / Q000378:metabolism*; D008324:Mammary Tumor Virus, Mouse / Q000276:immunology*; D051379:Mice; D008969:Molecular Sequence Data; D010455:Peptides / Q000235:genetics / Q000276:immunology; D011485:Protein Binding; D018089:Superantigens / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism / Q000821:virology
D000911:Antibodies, Monoclonal; D000949:Histocompatibility Antigens Class II; D010455:Peptides; D018089:Superantigens; D010450:Endopeptidases