Selective processing of β-endorphin in regions of porcine pituitary

Abstract
The prohormone of .beta.-endorphin is unusual in that it is the precursor of more than 1 biologically active peptide. The activation of this pro hormone, to produce ACTH, .alpha.-melanotropin (.alpha.-MSH) and .beta.-endorphin, would seem to be relatively complex as its processing pattern is known to differ between tissues. ACTH is produced in the anterior pituitary whereas .alpha.-MSH is formed in the pars intermedia; lipotropin and .beta.-endorphin seem to predominate in the anterior pituitary whereas .beta.-endorphin alone is presumably the principal component in the pars intermedia. A study is reported of the distribution of .beta.-endorphin-related peptides in various regions of porcine pituitary. The main products in the anterior pituitary were lipotropin and the potent analgesic form of .beta.-endorphin; the main products in the pars intermedia were the inactive lipotropin C''-fragment and its N-acetyl derivative. The processing of the C-terminal region of the .beta.-endorphin prohormone differs markedly between the 2 regions of porcine pituitary.