Murine complement component 3: genetic variation and linkage to H-2.

Two electrophoretic variants of murine complement component 3 (C3) were detected by using high-voltage electrophoresis of fresh mouse serum in agarose gels. Most of the inbred strains tested were homozygous for the S allele (for the slow-migrating variant); only four out of 46 strains had the alternative F allele (fast variant). Pen-bred Swiss-Webster animals belonged to one of three phenotypes--S, F, or SF--and the genes responsible for this variation segregated in a strictly Mendelian manner. In three such crosses, with 5* offspring, C3 segregated with H-2 in 46 instances, corresponding to a recombination frequency of approximately equal to 0.12.