title: SP-40,40 is an inhibitor of C5b-6-initiated haemolysis.
abstract: This study examines the function of SP-40,40, a newly identified component of the SC5b-9 complement complex, in the regulation of the terminal complement pathway. Purified SP-40,40 was shown to inhibit, in a dose-dependent manner, C5b-6-initiated haemolysis. Apparently additive inhibition was also demonstrated in conjunction with complement S-protein, although SP-40,40 appears to be the more potent inhibitor on an equimolar basis. The data suggest that SP-40,40, like S-protein, probably combines with the nascent C5b-7 complex, forming a cytolytically inactive SC5b-7 - SP-40,40 complex. Preparations of S-protein, purified by an established technique, were shown to be contaminated with SP-40,40. Preparations of affinity-purified SP-40,40 were also shown to contain S-protein, suggesting that these proteins may be partially complexed in plasma.
authors.affiliation: Department of Medicine, University of Melbourne, Australia.
authors.forename: B F
authors.initials: BF
authors.lastname: Murphy
authors.forename: J R
authors.initials: JR
authors.lastname: Saunders
authors.forename: M K
authors.initials: MK
authors.lastname: O'Bryan
authors.forename: L
authors.initials: L
authors.lastname: Kirszbaum
authors.forename: I D
authors.initials: ID
authors.lastname: Walker
authors.forename: A J
authors.initials: AJ
authors.lastname: d'Apice
mesh_terms: D000818:Animals; D001798:Blood Proteins / Q000276:immunology / Q000302:isolation & purification / Q000494:pharmacology*; D051152:Clusterin; D003165:Complement System Proteins / Q000502:physiology*; D004912:Erythrocytes / Q000187:drug effects / Q000276:immunology; D006023:Glycoproteins; D006168:Guinea Pigs; D006461:Hemolysis / Q000187:drug effects* / Q000276:immunology; D006801:Humans; D066298:In Vitro Techniques; D018832:Molecular Chaperones
chemical_list: D001798:Blood Proteins; C495242:CLU protein, human; D051152:Clusterin; D006023:Glycoproteins; D018832:Molecular Chaperones; C050974:complement C5b-6 complex; D003165:Complement System Proteins