Linked Life Data

2833909

Source:http://linkedlifedata.com/resource/pubmed/id/2833909

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
10
pubmed:dateCreated
1988-5-27
pubmed:abstractText
The phosphatase activities responsible for the sequential dephosphorylation of lysophosphatidylinositol 4,5-bisphosphate (lysoPtdIns(4,5)P2) to lysophosphatidylinositol that precedes reacylation in rat brain and liver microsomes were characterized. LysoPtdIns(4,5)P2 and the intermediate lysophosphatidylinositol 4-phosphate (lysoPtdIns4P) were hydrolyzed by two distinct phosphatase activities which were distinguishable by their substrate and cation requirements. The lysoPtdIns(4,5)P2 phosphatase activity was Mg2+ dependent and partially inhibited by Ca2+, excess Mg2+, and cationic detergent (cetyltrimethylammonium bromide). Activity was maximal at neutral (brain) or slightly alkaline (liver) pH when the Mg2+/lysoPtdIns(4,5)P2 molar ratio was 1.0 in the presence of bovine serum albumin (1 mg.mL-1). LysoPtdIns4P phosphatase activity did not require divalent cations (not inhibited by EDTA). This activity was inhibited by Ca2+, Mg2+, and substrate concentrations above 0.2 mM. Maximum activity was observed over a broad pH range (6.0-8.5). Both activities were inhibited by lysophosphatidylinositol and lysophosphatidylcholine, but not other lysophospholipids. The lysopolyphosphoinositides are most likely hydrolyzed by the same phosphatases that act on the diacylpolyphosphoinositides, since PtdIns(4,5)P2 and PtdIns4P were also hydrolysed by Mg2+-dependent and cation-independent phosphatases, respectively. Activities with the diacylpolyphosphoinositides differed only in their requirement of detergents for maximum activity in vitro. Specific activities for the diacyl and "lyso" forms of each substrate were very similar when suitably optimized reaction mixtures were used. The subcellular distributions of the two phosphatase activities in both brain and liver were the same when acting on diacyl- or lyso-polyphosphoinositides, as was their response to inhibitors. Alkaline, acid, phosphoprotein, and inositol-1-phosphate phosphatases did not contribute substantially to the hydrolysis of either lysoPtdIns4P or lysoPtdIns(4,5)P2, since the activities were not significantly inhibited by cysteine, dithiothreitol, NaF, or LiCl.(ABSTRACT TRUNCATED AT 250 WORDS)
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0829-8211
pubmed:author
pubmed:issnType
Print
pubmed:volume
65
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
890-8
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1987
pubmed:articleTitle
Identification of the phosphomonoesterases that hydrolyze lysopolyphosphoinositides in rat brain and liver.
pubmed:affiliation
Department of Biochemistry, Dalhousie University, Halifax, N.S., Canada.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't