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- Title
Human MHC Class I Antigens are Associated with a 90-kDa Cell Surface Protein.
- Authors
Ferm, M. T.; Grönberg, A.
- Abstract
Human MHC class I proteins are expressed on almost all nucleated cells as a heavy chain (about 45 kDa) non-covalently associated with β2-microglobulin (12 kDa). In this report we show that MHC class I (MHC-1) proteins can also be associated with a 90-kDa protein in the cell membrane. Surface-radiolabelled cells were treated with dithiobis succinimidyl propionate (DSP) in order to preserve multimer protein complexes during cell lysis. The lysates were immunoprecipitated and analysed by SDS-PAGE and autoradiography. Immunoprecipitation of human MHC-I proteins co-precipitated another protein of about 90 kDa in molecular weight p90. p90 was co-precipitated from all the MIIC'-I expressing cells tested: U9.17, Raji, Molt-4 and IFN-γ treated K562, but not from untreated, MHC-I negative K562. A 90-kDa protein was also co-precipitated with MHC-I from fresh peripheral blood mononuclear cells (PBMC). Furthermore, p90 was co-precipitated by different MoAhs lo the MHC-1 heavy chain or β2-microglobulin, but not by control antibodies. Two additional co-precipitating proteins al 34 kDa and 28 kDa were seen in MHC-I precipitates from Raji cells. Our results suggest that MHC-1 proteins and the 90-kDa protein are associated in the cell membrane, probably by a close but weak, non-covalent interaction. Two additional cell surface proteins at 34 kDa and 28 kDa seem to be MHC-I associated on Raji Burkilt's lymphoma cells.
- Subjects
PROTEINS; BIOMOLECULES; CELL membranes; MATHEMATICAL transformations; MOLECULAR weights; LINE geometry
- Publication
Scandinavian Journal of Immunology, 1991, Vol 34, Issue 2, p221
- ISSN
0300-9475
- Publication type
Article
- DOI
10.1111/j.1365-3083.1991.tb01540.x