The sun-tan hormone alpha-MSH is:
Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH2

The sun-tan hormone beta-MSH is:
Asp-Glu-Gly-Pro-Tyr-Lys-Met-Glu-His-Phe-Arg-Trp-Gly-Ser-Pro-Pro-Lys-Asp

This is the bovine case, from Sawyer et al. as quoted by Mac E. Hadley. The human case is still being investigated.