Calnexin associates with monomeric and oligomeric (disulfide-linked) CD3delta proteins in murine T lymphocytes.
The antigen-binding receptor expressed on most T lymphocytes consists of disulfide-linked clonotypic alphabeta heterodimers noncovalently associated with monomeric CD3gamma,delta,epsilon proteins and disulfide-linked zeta zeta homodimers, collectively referred to as the T cell antigen receptor (TCR) complex. Here, we examined and compared the disulfide linkage status of newly synthesized TCR proteins in murine CD4(+)CD8(+) thymocytes and splenic T cells. These studies demonstrate that CD3delta proteins exist as both monomeric and oligomeric (disulfide-linked) species that differentially assemble with CD3epsilon subunits in CD4(+)CD8(+) thymocytes and splenic T cells. Interestingly, unlike previous results on glucose trimming and TCR assembly of CD3delta proteins in splenic T cells (Van Leeuwen, J. E. M., and K. P. Kearse (1996) J. Biol. Chem. 271, 9660-9665), we found that glucose residues were not invariably removed from CD3delta glycoproteins prior to their assembly with CD3epsilon subunits in CD4(+)CD8(+) thymocytes. Finally, these studies show that calnexin associates with both monomeric and disulfide-linked CD3delta proteins in murine T cells. The data in the current report demonstrate that CD3delta proteins exist as both monomeric and disulfide-linked molecules in murine T cells that differentially associate with partner TCR chains in CD4(+)CD8(+) thymocytes and splenic T cells. These results are consistent with the concept that folding and assembly of CD3delta proteins is a function of their oxidation state.
Kearse
K P
KP
Department of Microbiology & Immunology, East Carolina University, School of Medicine, Greenville, North Carolina 27858-4353, USA. kearse@brody.med.ecu.edu
D000818:Animals; D015703:Antigens, CD / Q000276:immunology; D017252:CD3 Complex / Q000737:chemistry*; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D037281:Calnexin; D019281:Dimerization; D004220:Disulfides / Q000737:chemistry*; D008562:Membrane Glycoproteins / Q000737:chemistry; D051379:Mice; D011233:Precipitin Tests; D011487:Protein Conformation; D013154:Spleen / Q000502:physiology; D013601:T-Lymphocytes / Q000502:physiology*; D013950:Thymus Gland / Q000502:physiology
D015703:Antigens, CD; D017252:CD3 Complex; D002135:Calcium-Binding Proteins; D004220:Disulfides; D008562:Membrane Glycoproteins; D037281:Calnexin