J chain is covalently bound to both monomer subunits in human secretory IgA.

摘要: Previous work has established that the secretory component (SC) in human IgA is covalently linked to only one of two monomer subunits, but it not been clear whether J chain or both these subunits. In view asymmetry disulfide bonding between SC and an arrangement which follows interchange, several models for linkage bonds subunits were envisaged investigated. When sIgA was gel filtered through Sephadex G-200 acetic acid, a single major symmetrical peak eluted at front. This material contained SC, alpha L chains, all chain. The greater resolution afforded by polyacrylamide electrophoresis detergent confirmed contains no noncovalently components 150,000-200,000 molecular weight range. another series experiments Fc monomer, attached isolated after treatment with protease cyanogen bromide, investigated learn COOH-terminal octapeptides could be released reduction. results negative. available data thus favor model disulfide-bonded sIgA.