COMPLEMENT COMPONENT C3 - MOLECULAR-BASIS OF THE C3-ASTERISK-S025 VARIANT AND EVIDENCE FOR MOLECULAR HETEROGENEITY OF OTHER VARIANTS

Complement component 3 (C3) is the central molecule of the complement system. It displays a number of polymorphic variants with, as yet, unc lear functional consequences, We have investigated a number of rare C3 variants by PCR-SSCP (polymerase chain reaction-single strand conform ation polymorphism) analysis and could identify the molecular basis of a C3S025 variant. The decreased electrophoretic mobility of this pro tein is caused by the exchange of a neutral serine residue to an argin ine residue (positively charged), This exchange is unlikely to have fu nctional consequences as it maps to the C-terminus of the alpha-chain. C3 variants appear to have originated from various independent mutati ons as we could not detect this mutation in different allotypes.