title: Na+, K+-specific inhibition of protein and peptide hydrolyses by proteasomes from human hepatoma tissues.
abstract: Proteasomes were purified from human hepatoma tissues, and their sensitivities to Na+ and K+ were examined. At concentrations of 10 mM or more, these cations were found to inhibit completely polylysine-activated casein degradation by the purified proteasomes. They also strongly inhibited the hydrolyses of peptides, although to a lesser extent. On the other hand, they reversed the inhibitory and stimulatory effects of polylysine on the hydrolyses of Suc-Leu-Tyr-AMC and Cbz-Ala-Arg-Arg-MNA, respectively. These results suggest that Na+ and/or K+ may be involved in the regulation of intracellular protein breakdown by controlling the multicatalytic activity of proteasomes.
authors.affiliation: Department of Zoology, College of Natural Sciences, Seoul National University, South Korea.
authors.forename: J H
authors.initials: JH
authors.lastname: Seol
authors.forename: S C
authors.initials: SC
authors.lastname: Park
authors.forename: D B
authors.initials: DB
authors.lastname: Ha
authors.forename: C H
authors.initials: CH
authors.lastname: Chung
authors.forename: K
authors.initials: K
authors.lastname: Tanaka
authors.forename: A
authors.initials: A
authors.lastname: Ichihara
mesh_terms: D002118:Calcium / Q000494:pharmacology; D002364:Caseins / Q000378:metabolism; D002413:Cations, Divalent; D002414:Cations, Monovalent; D006801:Humans; D006868:Hydrolysis; D008099:Liver / Q000201:enzymology*; D008345:Manganese / Q000494:pharmacology; D010447:Peptide Hydrolases / Q000302:isolation & purification / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism*; D011107:Polylysine / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology*; D011480:Protease Inhibitors; D011506:Proteins / Q000378:metabolism*; D012964:Sodium / Q000494:pharmacology*
chemical_list: D002364:Caseins; D002413:Cations, Divalent; D002414:Cations, Monovalent; D010455:Peptides; D011480:Protease Inhibitors; D011506:Proteins; D011107:Polylysine; D008345:Manganese; D012964:Sodium; D010447:Peptide Hydrolases; D011188:Potassium; D002118:Calcium