Characterization of complementary deoxyribonucleic acid for precursor of porcine motilin

Cloned cDNAs encoding the precursor protein for motilin and a novel peptide, motilin-associated peptide, were isolated from a library derived from porcine intestinal mucosa mRNA. Nucleotide sequence analysis predicts a precursor protein of 119 amino acids including a signal peptide in direct linkage with the 22 amino acid sequence for motilin, and a 70 amino acid peptide of unknown function. The putative bioactive moieties are separated by Lys-Lys, dibasic residues that serve as substrates for cleavage by proteolytic maturation enzymes in many polyprotein precursors. While there is an abundant literature detailing a spectrum of tissues and cell types which express motilin like immunoreactivity, analysis of mRNA derived from many of these tissues suggests that the mRNA for the mucosal motilin precursor is only transcribed in this tissue. The nature of the immunoreactive material in the central nervous system and other peripheral tissues remains to be determined.