C1q component of complement binds to fibrinogen and fibrin

Journal Article · Tue Jan 12 04:00:00 EST 1988 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00401a073· OSTI ID:7000102

Entwistle, R A; Furcht, L T

The interaction of complement component C1q with fibrinogen and fibrin was studied by using a solid-phase direct binding assay. Scatchard analysis of radioiodinated fibrinogen binding to C1q indicated at least two high-affinity binding constants (Kd) calculated as 8.5 and 120 nM. In contrast, binding of radioiodinated fibrin to C1q showed only a single class of binding sites with a calculated Kd of 600 nM. Fibrinogen-C1q binding was shown to decrease as a function of increasing salt concentrations, indicating either the presence of charged amino acids in the binding sites or an ionic strength induced conformational dependency of the binding. In direct binding studies using isolated fragments of C1q, both the collagen-like domain of C1q and the globular domains of C1q were shown to bind fibrinogen, indicating at least one binding site for fibrinogen is located in each of the major domains of C1q. Addition of the thrombin-generated peptides of fibrinogen, fibrinopeptides A and B, enhanced C1q-fibrinogen binding, again indicating a complex binding interaction. These results indicate that C1q and fibrinogen are capable of high-affinity interactions that may serve to sequester these complexes in areas of tumors, immune complex deposition, or wounds.

• Research Organization: Univ. of Minnesota, Minneapolis (USA)
• OSTI ID: 7000102
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 27:1; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
BIOCHEMICAL REACTION KINETICS
BLOOD COAGULATION FACTORS
COAGULANTS
COMPLEMENT
DRUGS
FIBRIN
FIBRINOGEN
GLOBULINS
HEMATOLOGIC AGENTS
HEMOSTATICS
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
MEMBRANE PROTEINS
ORGANIC COMPOUNDS
PEPTIDES
PROTEINS
RADIOASSAY
REACTION KINETICS
RECEPTORS
SCLEROPROTEINS
TRACER TECHNIQUES