Genetic polymorphism and close linkage of two α1-protease inhibitors in horse serum

Abstract
Two-dimensional electrophoretic analysis of horse serum proteins was done by a 1st-dimension separation in agarose gel (pH 5.4) followed by a 2nd-dimension separation in horizontal polyacrylamide gel (pH 9.0). This method resulted in improved and reproducible separation of many .alpha.-globulins. Two groups of .alpha.1-globulins, designated Pi1 and Pi2, were protease inhibitors. Preliminary studies indicated that the Pi1 and Pi2 proteins differed from each other in MW and in protease inhibiting spectra. Extensive polymorphism was observed for both proteins. Family data supported the hypothesis that Pi1 and Pi2 types were controlled by autosomal codominant alleles. For both Pi1 and Pi2 systems, most of the homozygous types showed 2 fractions each while the heterozygous types had 4 fractions. Six Pi1 and 5 Pi2 alleles were observed in 2 breeds of Swedish horses. Complete genetic linkage was observed for Pi1 and Pi2 loci as no recombinant type was observed in 40 informative matings studied.