Document Detail

Protein phosphatase composition in the smooth muscle of guinea-pig ileum studied with okadaic acid and inhibitor 2.
MedLine Citation:
PMID:  2553005     Owner:  NLM     Status:  MEDLINE    
Using okadaic acid, a potent inhibitor of type 2A and type 1 protein phosphatases, and inhibitor 2, an intrinsic inhibitory factor of type 1 phosphatase, we characterized the phosphorylated myosin light-chain (PMLC) phosphatase activity in the smooth-muscle extracts of guinea-pig ileum. In the intact fibres the control activity was 254 +/- 13 nmol of Pi/min per g wet wt. (n = 15) against 32P-labelled PMLC (4 microM) from chicken gizzard. The following phosphatase fractions were identified: an inhibitor-2-sensitive (type 1) fraction (fractional activity = 35%), a Mg2+-dependent and okadaic acid-insensitive (type 2C) fraction (17%), and two type 2A-like fractions that had different susceptibility to okadaic acid. The type 2A-like fraction with lower affinity to okadaic acid accounted for 30% of the control activity. After the cell membrane was permeabilized by Triton X-100, more than 60% of this fraction remained and accounted for about 90% of the total activity, whereas the other fractions were nearly abolished. The type 2A-like fraction may be bound to some intracellular structure such as contractile proteins.
A Takai; M Troschka; G Mieskes; A V Somlyo
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Biochemical journal     Volume:  262     ISSN:  0264-6021     ISO Abbreviation:  Biochem. J.     Publication Date:  1989 Sep 
Date Detail:
Created Date:  1989-11-13     Completed Date:  1989-11-13     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  2984726R     Medline TA:  Biochem J     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  617-23     Citation Subset:  IM    
II. Physiologisches Institut, Universität Heidelberg, Federal Republic of Germany.
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MeSH Terms
Enzyme Inhibitors*
Ethers, Cyclic*
Guinea Pigs
Ileum / enzymology
Magnesium / physiology
Muscle Proteins
Muscle, Smooth / enzymology*
Myosin-Light-Chain Phosphatase
Okadaic Acid
Phosphoprotein Phosphatases / antagonists & inhibitors*,  metabolism
Reg. No./Substance:
0/Enzyme Inhibitors; 0/Ethers, Cyclic; 0/Ionophores; 0/Muscle Proteins; 0/Proteins; 0/protein phosphatase inhibitor-2; 7439-95-4/Magnesium; 78111-17-8/Okadaic Acid; EC Phosphatases; EC Phosphatase

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