Figure 4.23. The IgM and IgA molecules can form multimers.

Figure 4.23The IgM and IgA molecules can form multimers

IgM and IgA are usually synthesized as multimers in association with an additional polypeptide chain, the J chain. In pentameric IgM, the monomers are cross-linked by disulfide bonds to each other and to the J chain. The top left panel shows an electron micrograph of an IgM pentamer, showing the arrangement of the monomers in a flat disc. IgM can also form hexamers that lack a J chain but are more efficient in complement activation. In dimeric IgA, the monomers have disulfide bonds to the J chain as well as to each other. The bottom left panel shows an electron micrograph of dimeric IgA. Photographs (× 900,000) courtesy of K.H. Roux and J.M. Schiff.

From: Structural variation in immunoglobulin constant regions

Cover of Immunobiology
Immunobiology: The Immune System in Health and Disease. 5th edition.
Janeway CA Jr, Travers P, Walport M, et al.
New York: Garland Science; 2001.
Copyright © 2001, Garland Science.

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