Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01189 (beta-endorphin)
 21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We examined by immunocytochemistry the localization of cathepsins B and H in corticotrophs and melanotrophs in anterior and intermediate lobes of rat pituitary gland, using monospecific antibodies to cathepsins B and H. In serial semithin sections, immunodeposits for cathepsin H were detected throughout the cytoplasm of cells immunoreactive for ACTH and alpha-MSH in anterior and intermediate pituitary. Granular immunodeposits for cathepsin B were demonstrated in anterior and intermediate cells. Double immunostaining colocalized immunogold particles for cathepsin H and ACTH or alpha-MSH in secretory granules of corticotrophs or melanotrophs, whereas those for cathepsin B were detected only in their lysosomes. Enzyme assay demonstrated cathepsin B activity in both anterior and intermediate pituitary tissue, but did not detect cathepsin H activity in the intermediate pituitary. Western blotting, however, revealed the presence of cathepsin H and cystatin beta in intermediate pituitary. These results suggest that cathepsin B plays a role in protein degradation in lysosomes of corticotrophs and melanotrophs. Moreover, the presence of cathepsin H in secretory granules of the cells may indicate that the enzyme participates in the activation of secretory products.
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PMID:Immunocytochemical localization of cathepsins B and H in corticotrophs and melanotrophs of rat pituitary gland. 215 33

Lysates of secretory granules from rat pituitary neurointermediate lobes were incubated with [3H]arginine- or [3H]phenylalanine-labeled toad pro-opiocortin. The processed products formed were identified by immunoprecipitation with adrenocorticotropin (ACTH) and endorphin antisera and by migration behavior on acid/urea/polyacrylamide gels. Pro-opiocortin was cleaved by the proteolytic activity in the secretory granule fraction to approximately 21,000 Mr ACTH, approximately 13,000 Mr ACTH, alpha-melanotropin, 16,000 Mr NH2-terminal glycopeptide, beta-lipotropin, and an endorphin-related peptide. Characterization of this pro-opiocortin-converting activity shows that it (i) is present in membrane and soluble fractions of the granule lysates, (ii) has a pH optimum of 5.0, (iii) appears to cleave at pairs of basic amino acid residues in the precursor, and (iv) is inhibited by leupeptin, pepstatin A, and p-chloromercuribenzoate but not diisopropyl fluorophosphate, N alpha-p-tosyl-L-lysine chloromethyl ketone hydrochloride, chloroquine, or EDTA. These inhibitor studies suggest that the converting-enzyme activity is due to an acid thiol, arginyl protease, distinct from any known cathepsin B-like activity.
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PMID:Characterization of pro-opiocortin-converting activity in purified secretory granules from rat pituitary neurointermediate lobe. 627 79