GONUTS has been updated to MW1.31 Most things seem to be working but be sure to report problems.

Have any questions? Please email us at ecoliwiki@gmail.com

PMID:11367526

From GONUTS
Jump to: navigation, search
Citation

Rawal, N and Pangburn, MK (2001) Structure/function of C5 convertases of complement. Int. Immunopharmacol. 1:415-22

Abstract

C5 convertases are serine proteases that cleave both C3 and C5. Alternative pathway C3/C5 convertases formed with monomeric C3b (C3b,Bb) because of their weak interaction with C5 primarily cleave C3 thereby opsonizing the cell surface with C3b. In contrast, C3/C5 convertases formed with a high density of C3b/cell exhibit higher affinities for C5 as indicated by Km values well below the physiological concentration of C5 in blood. These C3/C5 convertases bind C5 efficiently and cleave it at a velocity approaching Vmax thereby switching the enzyme from C3 cleavage to production of the cytolytic C5b-9 complex. Studies of the structure of C3/C5 convertases have postulated that C4b-C3b and C3b-C3b dimers from high affinity C5 binding sites while indel studies have shown two binding sites in C5 for the convertase in addition to the C5 cleavage site. Together, these studies indicate that with increasing deposition of C3b on the surface, C3b complexes are formed which through multivalent attachment bind the substrate C5 with higher affinities, thereby converting the low affinity C3/C5 convertases to high affinity C5 convertases. The process underlying the formation of high affinity C5 convertases during complement activation is discussed.

Links

PubMed

Keywords

Animals; Binding Sites; Complement C3/metabolism; Complement C3-C5 Convertases/chemistry; Complement C3-C5 Convertases/metabolism; Complement C5/metabolism; Humans; Kinetics; Models, Biological

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

HUMAN:CFAB

enables

GO:0001848: complement binding

ECO:0000304: author statement supported by traceable reference used in manual assertion

F

Seeded From UniProt

complete


See also

References

See Help:References for how to manage references in GONUTS.