title: Multiple forms of complement C3 in trout that differ in binding to complement activators.
abstract: In all other species analyzed to date, the functionally active form of complement component C3 exists as the product of a single gene. We have now identified and characterized three functional C3 proteins (C3-1, C3-3, and C3-4) in trout that are the products of at least two distinct C3 genes. All three proteins are composed of an alpha-and a beta-chain and contain a thioester bond in the alpha-chain. However, they differ in their electrophoretic mobility, glycosylation, reactivity with monospecific C3 antibodies, and relative ability to bind to various surfaces (zymosan, Escherichia coli, erythrocytes). A comparison of the partial amino acid sequences of the three proteins showed that the amino acid sequence identity/similarity of C3-3 to C3-4 is 87/91%, while that of C3-3 and C3-4 to C3-1 is 51.5/65.5% and 60/73% respectively. Thus, trout possess multiple forms of functional C3 that represent the products of several distinct genes and differ in their ability to bind covalently to various complement activators.
authors.affiliation: Department of Pathology, University of Pennsylvania, Philadelphia 19104-6079.
authors.forename: J O
authors.initials: JO
authors.lastname: Sunyer
authors.forename: I K
authors.initials: IK
authors.lastname: Zarkadis
authors.forename: A
authors.initials: A
authors.lastname: Sahu
authors.forename: J D
authors.initials: JD
authors.lastname: Lambris
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003167:Complement Activation; D003176:Complement C3 / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D016384:Consensus Sequence; D003429:Cross Reactions; D017931:DNA Primers / Q000737:chemistry; D006801:Humans; D008969:Molecular Sequence Data; D017686:Oncorhynchus mykiss / Q000235:genetics / Q000276:immunology*; D011485:Protein Binding; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship
chemical_list: D003176:Complement C3; D017931:DNA Primers