PMID: 1194853Nov 1, 1975Paper

C1 fixation and classical complement pathway activation by a fragment of the Cmu4 domain of IgM

The Journal of Experimental Medicine
M M HurstJ C Bennett

Abstract

A 56 residue fragment derived from a Waldenströme IgM protein and consisting of 24 residues of the amino-terminal portion of the Cmu4 domain disulfide bonded to 32 residues of the carboxy-terminal region of the loop has been shown to fix active C1 (C1) in a C1-fixation assay. Cleavage of the disulfide bond within the CH4 fragment resulted in a marked decrease of C1-fixing ability, although the isolated A and B fragments did retain a limited ability to fix C1. Upon incubation with normal human serum the intact CH4 fragment and equal molar amounts of the isolated A and B peptides consumed C4 suggesting that the C1-activating determinant of IgM remains intact in these three fragments. Furthermore, on a molar basis the intact or the reduced CH4 fragment consumed C4 as effectively as each of its component chains suggesting that transient binding of C1 by the individual A and B peptide chains is sufficient to activate C1. On the basis of these observations it is proposed that a classical complement fixation function, i.e. C1 binding and activation, can be localized within a region of the IgM molecule corresponding to the Cmu4 domain.

References

Oct 1, 1974·The Journal of Experimental Medicine·M M HurstJ C Bennett
Apr 28, 1972·Biochemical and Biophysical Research Communications·K J DorringtonM W Turner
Feb 21, 1967·Biochimica Et Biophysica Acta·K R Woods, K T Wang

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Citations

Sep 1, 1978·Immunochemistry·J L Winkelhake
Feb 1, 1978·Immunochemistry·T Y Lin, D S Fletcher
Aug 1, 1989·Molecular Immunology·M MatsumotoH Kitamura
Apr 1, 1989·Immunology Today·A C Davis, M J Shulman
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Jul 29, 2006·Clinica Chimica Acta; International Journal of Clinical Chemistry·Thiruma V ArumugamStephen M Taylor
Jan 1, 1980·Scandinavian Journal of Infectious Diseases. Supplementum
Nov 17, 2020·Frontiers in Immunology·Katelyn JonesSabelo Hadebe
Sep 1, 1982·Molecular and Cellular Biology·M J ShulmanG Köhler

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