title: Na+,K(+)-ATPase inhibition by an endogenous peptide, SPAI-1, isolated from porcine duodenum.
abstract: SPAI-1, a peptide isolated from porcine duodenum, has been shown to inhibit Na+,K(+)-ATPase in vitro (Araki et al. (1989) Biochem. Biophys. Res. Commun. 164, 496-502). The characteristics of ATPase inhibition by this novel peptide were examined. SPAI-1 inhibited Na+,K(+)-ATPase preparations isolated from various organs of dog or rat or from sheep kidney with similar potency. Three isoforms of rat Na+,K(+)-ATPase had similar sensitivity to inhibition by SPAI-1 although these isoforms had remarkable differences in their sensitivity to the inhibitory effect of ouabain. Ca(2+)-ATPase isolated from the sarcoplasmic reticulum of rabbit skeletal muscle was insensitive to inhibition by SPAI-1. Ouabain-insensitive Mg(2+)-ATPase activity was unaffected by low concentrations of SPAI-1, but was stimulated at high concentrations. SPAI-1 inhibited H+,K(+)-ATPase from hog stomach in concentrations similar to that required for Na+,K(+)-ATPase inhibition. These results indicate that SPAI-1 is a specific inhibitor for monovalent cation transporting ATPases.
authors.affiliation: Department of Pediatric Pharmacology, National Children's Medical Research Center, Tokyo, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Ishizuka
authors.forename: Y
authors.initials: Y
authors.lastname: Fukushima
authors.forename: O
authors.initials: O
authors.lastname: Urayama
authors.forename: T
authors.initials: T
authors.lastname: Akera
mesh_terms: D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors; D000818:Animals; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D004285:Dogs; D004386:Duodenum / Q000737:chemistry*; D004591:Electrophoresis, Polyacrylamide Gel; D017506:H(+)-K(+)-Exchanging ATPase; D007527:Isoenzymes / Q000037:antagonists & inhibitors; D007700:Kinetics; D009928:Organ Specificity; D010042:Ouabain / Q000494:pharmacology; D011506:Proteins / Q000302:isolation & purification / Q000494:pharmacology*; D011817:Rabbits; D051381:Rats; D012756:Sheep; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors*; D013552:Swine; D014018:Tissue Distribution
chemical_list: D007527:Isoenzymes; D011506:Proteins; C061401:SPAI-1 protein, Sus scrofa; D010042:Ouabain; D000251:Adenosine Triphosphatases; D017506:H(+)-K(+)-Exchanging ATPase; D000252:Calcium-Transporting ATPases; D000254:Sodium-Potassium-Exchanging ATPase