Surface-associated C3bBb Cell surface:C3b:Factor Bb:Properdin Properdin stabilizes C3b:Bb bound to cell surfaces Authored: de Bono, B, 2004-08-04 09:17:50 C3b:Bb is naturally labile with a half-life of ~90 s; association of the complex with properdin extends the half-life to ~30 min. (Medicus et al. 1976). Properdin is found in the blood as a mixture of multivalent oligomers: 30% dimers, 45% trimers, 10% tetramers, and 15% higher oligomers. Monomers associate with one another in a head-to-tail arrangement, producing closed circular structures (Smith et al. 1984). These features suggest that the properdin oligomer associated with a C3b:Bb complex on a surface such as a cell membrane can facilitate recruitment of additional C3b:Bb complexes to the site (Farries et al. 1988; Hourcade 2006). Pubmed16301317 Pubmed3421908 Pubmed6707020 Pubmed978134 Reactome Database ID Release 43173754 Reactome, http://www.reactome.org ReactomeREACT_8018 Reviewed: D'Eustachio, P, 2006-07-03 21:35:13 Properdin oligomer