Molecular characterization of the Ss and Slp (C4) proteins of the mouse H-2 complex: subunit composition, chain size polymorphism, and an intracellular (PRO-Ss) precursor
Roos, M.H.; Atkinson, J.P.; Shreffler, D.C.
Journal of Immunology 121(3): 1106-1115
1978
ISSN/ISBN: 0022-1767 PMID: 690436 Document Number: 134124
Adherent peritoneal cells, presumably macrophages, from mice of a number of congenic strains when cultured in vitro in medium containing 14C-labeled amino acids synthesized the Ss protein (mouse C4 described recently) was demonstrated in lysates of cultured peritoneal cells. The structural homologies of the mouse Ss-Slp and human and guinea pig C4 proteins were confirmed. Ss and Slp-antisera may define 2 similar, but structurally distinct subclasses of mouse C4 that are apparently controlled by 2 discrete structural genes in the S regions of Slp-positive strains. Each of these structural genes may code for a single polypeptide precursor for the native Slp-positive and Slp-negative Ss molecules. The differences in the MW of the .alpha.- and .gamma.-chains of these 2 Ss subclasses may reflect a mutational shift in the site of the proteolytic cleavage step that releases the chains.