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Potassium ion-activated hydrolysis of p-nitrophenyl phosphate in pancreatic islet-cell membranes

Lernmark, A. LU orcid ; Parman, A. and Taljedal, I. B. (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.

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author
; and
publishing date
type
Contribution to journal
publication status
published
in
Biochemical Journal
volume
166
issue
2
pages
181 - 187
publisher
Portland Press
external identifiers
  • scopus:0017654548
  • pmid:20876
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}},
}