Sheep wool (glycine + tyrosine)-rich keratin genes. A family of low sequence homology

We report the isolation and complete nucleotide sequence of genes encoding the two major high-(glycine + tyrosine) (HGT) keratins of sheep wool in separate genomic clones. The genes have negligible sequence homology except for an 18-bp conserved element immediately preceding the initiation codon. The same element has been found in the corresponding position of a number of co-expressed high-sulphur (HS) keratin genes and may therefore represent a common element between these wool intermediate-filament-associated proteins. As seen for the HS keratin genes, the HGT keratin genes also lack introns. Southern blot data show that both HGT genes are unique in the sheep genome, indicating that the observed heterogeneity of the HGT protein class may not be as complex as previously suggested.