Mammalian and avian PO protein of the peripheral nervous system myelin are different.

1. The mammalian PO gene exhibits low homology to the avian PO gene and transcript. 2. The avian PO mRNA is smaller than the mammalian mRNA. 3. The primary structure of mammalian and avian PO proteins differ in their molecular weight, isoelectric point, and chymotryptic peptide pattern. 4. Similarity between the PO proteins is indicated by immuno-cross-reactivity of the anti-chicken PO IgG to mammalian PO proteins. 5. Similarities at the level of amino acid sequence could provide insight on the structure and function of the PO protein.