Molecular analysis of a new splice variant of the human melanocortin‐1 receptor

The primary hormonal regulator of pigmentation is melanocyte stimulating hormone derived from proopiomelanocortin by proteolytic processing. The melanocortin-1 receptor serves a key role in the regulation of pigmentation. We describe the identification of the first intron within a melanocortin receptor. A new melanocortin-1 receptor isoform, generated by alternative mRNA splicing, encodes an additional 65 amino acids at the predicted intracellular, C-terminal tail of the melanocortin-1 receptor. When expressed in heterologous cells, the new spliced form of the melanocortin-1 receptor (melanocortin-1 receptor B) appears pharmacologically similar to the non-spliced melanocortin-1 receptor. Melanocortin-1 receptor B is expressed in testis, fetal heart and melanomas.