C1q--how many functions? How many receptors?
C1, the first component of the classical pathway of complement activation is a complex of three proteins called C1q, C1r and C1s. Normally, C1q binding to aggregated IgG molecules results in activation of the classical pathway of complement. However, C1q has a number of other observed functions, not directly related to complement, that could be mediated by recently identified binding proteins acting as cell-surface receptors or soluble modulators of C1q-mediated functions. This article discusses the various activities of C1q and the evidence that these functions might be influenced by both membrane-bound and soluble C1q-binding proteins.
Eggleton
P
P
Dept of Biochemistry, University of Oxford, UK. eggleton@bioch.ox.ac.uk
Reid
K B
KB
Tenner
A J
AJ
D000818:Animals; D002352:Carrier Proteins; D002462:Cell Membrane / Q000378:metabolism; D015922:Complement C1q / Q000378:metabolism*; D006801:Humans; D018960:Hyaluronan Receptors; D008024:Ligands; D008562:Membrane Glycoproteins; D024101:Mitochondrial Proteins; D011951:Receptors, Complement / Q000378:metabolism*; D012995:Solubility
C087299:C1QBP protein, human; D002352:Carrier Proteins; D018960:Hyaluronan Receptors; D008024:Ligands; D008562:Membrane Glycoproteins; D024101:Mitochondrial Proteins; D011951:Receptors, Complement; C032402:complement 1q receptor; D015922:Complement C1q