Complete amino acid sequence of mouse pro-opiomelanocortin derived from the nucleotide sequence of pro-opiomelanocortin cDNA.

Polyadenylated RNA was isolated from a mouse pituitary tumor cell line (AtT-20/D16v) which synthesizes and secretes adrenocorticotropic hormone and beta-endorphin. The RNA was used to construct a cDNA library by a double linker technique and the library was screened for pro-opiomelanocortin (POMC) sequences. One recombinant plasmid, pMKSU16, contained a 923-base pair insert comprising the entire POMC-coding sequence as well as 98 bases of 5' noncoding and 5 bases of 3' noncoding sequence. The protein sequence predicted by the cDNA shows mouse POMC to consist of 235 amino acids with seven potential tryptic cleavage sites consisting of pairs of basic amino acid residues. Comparison with the previously published bovine POMC sequence suggests certain regions of POMC are highly conserved between the two species, particularly the regions corresponding to the alpha-, beta-, and gamma-melanocyte-stimulating hormones.