Differential Regulation of ACTH and β-Endorphin by Controlled Processing
It is well known that the biologically active peptides ACTH and β-endorphin are formed from a single prohormone, pro-opiomelanocortin (POMC), and there have been several reports that the two peptides are released concomitantly (Allen et al., 1982; Mains and Eipper, 1981). However it appears that these precursor related peptides are not always released in equivalent amounts. It has been shown, for example, that stimulation of AtT-20 tumour cells with CRF leads to a non-stoichiometric release (Hook et al., 1982) and in vivo evidence has been obtained that application of certain forms of stress to rats leads to preferential secretion of ACTH (DeSouza and Van Loon, 1985). If it can be shown that mechanisms exist for the excision of one region of a prohormone rather than another, it would be reasonable to expect that the processing of multifunctional prohormones may be flexible and that various combinations of activities may be generated to fulfil complex physiological functions.
KeywordsCorticotropin Release Factor Anterior Pituitary Cell Pituitary Tumour Cell Elution Position Corticotropin Release Factor
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