Isolation and structure of another beta-melanotropin from salmon pituitary glands.

A heptadecapeptide has been isolated from a side fraction of beta-MSH in an acid acetone extract of the pituitary of the salmon, Oncorhynchus keta. The sequence analysis revealed the peptide to be another form of salmon beta-MSH with following primary structure; H-Asp-Gly-Ser-Tyr-Arg-Met-Gly-His-Phe-Arg-Trp-Gly-Ser-Pro-Thr-Ala-Ile-OH. The findings of two distinctive beta-MSHs as well as two endorphins as reported previously in the pituitary extract suggest that the teleost pituitary may secrete two different precursor molecules, beta-LPH, and thus also higher molecular weight precursors.