Subunit size of enzymes and genetic heterozygosity in vertebrates.

There is a small but significant positive correlation between individual locus estimates of heterozygosity and subunit molecular weight in vertebrate dimeric enzymes. This correlation is smaller than that previously shown to exist for Drosophila dimers, and some possible reasons for this are explored. Data for vertebrate tetrameric enzymes are less extensive but appear to give similar trends to those shown by dimers. It is concluded that enzyme heterozygosity is influenced by both subunit size and quaternary structure.