title: Characterization of multiple forms of porcine anterior pituitary proopiomelanocortin amino-terminal glycopeptide.
abstract: Chromatography on a molecular sieve column of a preparation of porcine proopiomelanocortin N-terminal glycopeptide purified from anterior pituitary resulted in the isolation of three forms of the peptide with respective apparent Mr 21 000, 17 500, and 13 500 on polyacrylamide/sodium dodecyl sulfate gel. Determination of the amino acid composition of each peptide revealed that the form with a molecular weight of 17 500 corresponds to the 80 amino acid residue porcine N-terminal glycopeptide (PNT 1-80) previously characterized [Larivière, N., Seidah, N.G., & Chrétien, M. (1981) Int. J. Pept. Protein Res. 18, 487-491]. The forms with molecular weight of 21 000 and 13 500 correspond respectively to longer and shorter forms of the N-terminal glycopeptide. The high molecular weight form contains 107 amino acid residues. Sequencing of the fragments obtained after cleavage of the molecule with cyanogen bromide and Myxobacter Lys-C protease indicated that an extension of 27 amino acid residues is linked to PNT 1-80 through a -Lys-Arg-sequence. The sequence of the extension is reported. The low molecular weight form corresponds to the first 61 residues of PNT 1-80. Pronase digestion of the peptide and dansylation of the digest revealed the presence of a residue of phenylalanine amide at position 61. A general model for the maturation of the N-terminal glycopeptide of proopiomelanocortin in porcine anterior pituitary is presented.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D006020:Glycopeptides / Q000302:isolation & purification*; D006801:Humans; D008970:Molecular Weight; D010446:Peptide Fragments / Q000302:isolation & purification*; D010903:Pituitary Gland, Anterior / Q000032:analysis*; D010907:Pituitary Hormones / Q000302:isolation & purification*; D011333:Pro-Opiomelanocortin; D051381:Rats; D013552:Swine
chemical_list: D006020:Glycopeptides; D010446:Peptide Fragments; D010907:Pituitary Hormones; C028182:proopiocortin fragments; D011333:Pro-Opiomelanocortin