Linker histone H1.b is polymorphic in grey partridge (Perdix perdix)

This study was aimed at characterizing allelic variations of erythrocyte histone H1.b by comparing the electrophoretic patterns of histone H1.b from individuals of grey partridge (Perdix perdix) population. As two alloforms, H1.b1 and H1.b2, were discerned in the screening gels, the histone H1.b was regarded to be a polymorphic protein encoded by a gene with two codominant alleles, b1 and b2, at a locus. The tested population was found to be at Hardy-Weinberg equilibrium (chi2 = 0.834, p = 0.361), with only a minor heterozygote deficiency (fixation index F = 0.136). Since the histone H1.b alloforms were identified in a two-dimensional gel containing sodium dodecyl sulfate, with no significant differences in their migration pattern in an one-dimensional acetic acid polyacrylamide gel, we assumed that the H1.b alloforms possessed a similar net charge and differed in their apparent molecular weights. A comparison of N-bromosuccinimide-cleaved and alpha-chymotrypsin-digested products of histone H1.b alloforms revealed slight differences in the velocity of C-terminal peptides and a similarity in migration of their N-terminal peptides in one-dimensional sodium dodecyl sulfate-polyacrylamide gel. Therefore, it seemed that the histone H1.b alloforms might differ in this amino acid sequence in a protein segment between N-bromosuccinimide cleavage site and the very C-terminus.