Developmental regulation of IgM secretion: The role of the carboxy-terminal cysteine

Roberto Sitia, Michael Neuberger, Cristina Alberini, Paola Bet, Anna Fra, Caterina Valetti, Gareth Williams, Cesar Milstein

Research output: Contribution to journalArticlepeer-review


B lymphocytes do not secrete IgM, and plasma cells only secrete IgM polymers. Here we show that both events are attributable to the tailpiece found at the carboxyl terminus of μs chains, and we specifically implicate Cys-575. Thus, if Cys-575 was mutated, IgM was secreted by B cells. Similarly, a mutant IgG containing a μs tailpiece became largely retained within the cell; secretion was restored upon mutation of the tailpiece cysteine. Removal of Cys-575 also allowed hypersecretion of monomeric IgM by plasmacytoma cells. Following further removal of Cμ1, heavy chains were secreted in the absence of light chains. Thus, in B and plasma cells, Cys-575 is involved both in the polymerization of IgM and in intracellular retention of unpolymerized intermediates.

Original languageEnglish (US)
Pages (from-to)781-790
Number of pages10
Issue number5
StatePublished - Mar 9 1990

ASJC Scopus subject areas

  • General Biochemistry, Genetics and Molecular Biology


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