Roles of heavy and light chains in IgM polymerization.
Proc Natl Acad Sci U S A
; 92(11): 4912-6, 1995 May 23.
Article
in En
| MEDLINE
| ID: mdl-7761423
ABSTRACT
IgM antibodies are secreted as multisubunit polymers that consist of as many as three discrete polypeptides mu heavy chains, light (L) chains, and joining (J) chains. We wished to determine whether L chains that are required to confer secretory competence on immunoglobulin molecules must be present for IgM to polymerize--that is, for intersubunit disulfide bonds to form between mu chains. Using a L-chain-loss variant of an IgM-secreting hybridoma, we demonstrated that mu chains were efficiently polymerized independent of L chains, in a manner similar to that observed for conventional microL complexes, and that the mu polymers incorporated J chain. These mu polymers were not secreted but remained associated with the endoplasmic reticulum-resident chaperone BiP (GRP78). This finding is consistent with the endoplasmic reticulum being the subcellular site of IgM polymerization. We conclude that mu chain alone has the potential to direct the polymerization of secreted IgM, a process necessary but not sufficient for IgM to attain secretory competence.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Immunoglobulin M
/
Immunoglobulin Heavy Chains
/
Immunoglobulin Light Chains
Limits:
Animals
Language:
En
Journal:
Proc Natl Acad Sci U S A
Year:
1995
Type:
Article
Affiliation country:
United States