Potassium ion-activated hydrolysis of p-nitrophenyl phosphate in pancreatic islet-cell membranes
(1977) In Biochemical Journal 166(2). p.181-187- Abstract
Hydrolysis of p nitrophenyl phosphate was measured in a fraction enriched in plasma membranes from pancreatic islets of non inbred ob/ob mice. Hydrolysis was stimulated by K+ (10mM) in the pH range 5-10; a small peak of K+ induced activation was observed between pH 7.5 and 8. Both the K+ induced activation and the hydrolysis in the absence of K+ were Mg2+ dependent; maximum activation was obtained with 10mM K+ plus 5mM Mg2+. Rb+ was as effective an activator as K+. Ouabain was inhibitory, the effect being inversely related to the K+ concentration; 0.1-0.2 mM ouabain caused about 50% inhibition in the presence of 1mM... (More)
Hydrolysis of p nitrophenyl phosphate was measured in a fraction enriched in plasma membranes from pancreatic islets of non inbred ob/ob mice. Hydrolysis was stimulated by K+ (10mM) in the pH range 5-10; a small peak of K+ induced activation was observed between pH 7.5 and 8. Both the K+ induced activation and the hydrolysis in the absence of K+ were Mg2+ dependent; maximum activation was obtained with 10mM K+ plus 5mM Mg2+. Rb+ was as effective an activator as K+. Ouabain was inhibitory, the effect being inversely related to the K+ concentration; 0.1-0.2 mM ouabain caused about 50% inhibition in the presence of 1mM K+, but had no demonstrable effect in the presence of 4-5 mM K+. The K+ stimulated activity was markedly inhibited by 0.1 mM ATP, 35-140 mM Na+, or 0.01 mM p chloromercuribenzenesulphonic acid. Similarities to Rb+ accumulation suggest that catalysis of univalent cation flow in pancreatic β cells may be coupled to a phosphoryl transfer reaction with ATP as natural substrate or regulator.
(Less)
- author
- Lernmark, A. LU ; Parman, A. and Taljedal, I. B.
- publishing date
- 1977-01-01
- type
- Contribution to journal
- publication status
- published
- in
- Biochemical Journal
- volume
- 166
- issue
- 2
- pages
- 181 - 187
- publisher
- Portland Press
- external identifiers
-
- pmid:20876
- scopus:0017654548
- ISSN
- 0264-6021
- DOI
- 10.1042/bj1660181
- language
- English
- LU publication?
- no
- id
- 92118b2d-5772-435d-ae17-130616181f27
- date added to LUP
- 2019-09-18 12:09:53
- date last changed
- 2024-03-13 08:28:38
@article{92118b2d-5772-435d-ae17-130616181f27, abstract = {{<p>Hydrolysis of p nitrophenyl phosphate was measured in a fraction enriched in plasma membranes from pancreatic islets of non inbred ob/ob mice. Hydrolysis was stimulated by K<sup>+</sup> (10mM) in the pH range 5-10; a small peak of K<sup>+</sup> induced activation was observed between pH 7.5 and 8. Both the K<sup>+</sup> induced activation and the hydrolysis in the absence of K<sup>+</sup> were Mg<sup>2+</sup> dependent; maximum activation was obtained with 10mM K<sup>+</sup> plus 5mM Mg<sup>2+</sup>. Rb<sup>+</sup> was as effective an activator as K<sup>+</sup>. Ouabain was inhibitory, the effect being inversely related to the K<sup>+</sup> concentration; 0.1-0.2 mM ouabain caused about 50% inhibition in the presence of 1mM K<sup>+</sup>, but had no demonstrable effect in the presence of 4-5 mM K<sup>+</sup>. The K<sup>+</sup> stimulated activity was markedly inhibited by 0.1 mM ATP, 35-140 mM Na<sup>+</sup>, or 0.01 mM p chloromercuribenzenesulphonic acid. Similarities to Rb<sup>+</sup> accumulation suggest that catalysis of univalent cation flow in pancreatic β cells may be coupled to a phosphoryl transfer reaction with ATP as natural substrate or regulator.</p>}}, author = {{Lernmark, A. and Parman, A. and Taljedal, I. B.}}, issn = {{0264-6021}}, language = {{eng}}, month = {{01}}, number = {{2}}, pages = {{181--187}}, publisher = {{Portland Press}}, series = {{Biochemical Journal}}, title = {{Potassium ion-activated hydrolysis of p-nitrophenyl phosphate in pancreatic islet-cell membranes}}, url = {{http://dx.doi.org/10.1042/bj1660181}}, doi = {{10.1042/bj1660181}}, volume = {{166}}, year = {{1977}}, }