Different assembly species of IgM are directed to distinct degradation sites along the secretory pathway

E. Rabinovich, S. Bar-Nun, R. Amitay, I. Shachar, B. Gur, M. Taya, J. Haimovich

Research output: Contribution to journalArticlepeer-review

Abstract

In 38C B lymphocytes the membrane form of IgM is displayed on the cell surface whereas the secretory form of IgM is degraded. In the EH cell line, a light chain-deficient variant of 38C cells, the μ heavy chains are partially assembled with surrogate light chains characteristic of pre-B cells. In these cells neither the membrane (μm) nor the secretory (μs) forms of the μ heavy chain reach their final destination, and both are rapidly degraded. The degradation of μ chains in EH cells, like that of μs in 38C cells, is nonlysosomal and occurs prior to the trans-Golgi. However, while μs degradation in 38C cells is inhibited by brefeldin A, in EH cells μs and μm are retained and degraded by a brefeldin A-insensitive mechanism. These results indicate that degradation in EH cells occurs within the endoplasmic reticulum, whereas degradation in 38C cells requires exit from this compartment. Thus, μ heavy chains can be degraded in multiple sites along the secretory pathway. The location of the degradation process is determined by the developmentally regulated assembly species of the μ chains with either 'classical' or surrogate light chains.

Original languageEnglish
Pages (from-to)24145-24148
Number of pages4
JournalJournal of Biological Chemistry
Volume268
Issue number32
StatePublished - 1993

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