Linked Life Data

2906138

Source:http://linkedlifedata.com/resource/pubmed/id/2906138

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1199
pubmed:dateCreated
1989-3-23
pubmed:abstractText
Several lines of experimental evidence indicate the involvement of a guanine nucleotide-dependent protein (G-protein) in the hormone-stimulated hydrolysis of phosphatidylinositol(4,5)-bisphosphate (PtdIns(4,5)P2). However, the shortcomings of available procedures for cell-free assay of hormone-stimulated phosphoinositidase C (PIC) have limited our current understanding of the molecular and mechanistic details of PIC regulation. We recently have proposed that turkey erythrocyte membranes may provide a valuable model system for studies of G-protein-dependent PtdIns(4,5)P2 hydrolysis. The membranes can be simply prepared from [3H]inositol-labelled erythrocytes and they contain a PIC activity that hydrolyses endogenous phosphoinositides and is exquisitively sensitive to guanine nucleotides. PtdIns(4,5)P2 is the principal substrate for this enzyme, there being relatively little direct hydrolysis of phosphatidylinositol 4-phosphate and no detectable hydrolysis of PtdIns. The membranes also contain a purinoceptor of the P2y subclass that is efficiently coupled to PtdIns(4,5)P2 hydrolysis both in intact cells and in the isolated membranes. 2-Methylthioadenosine trisphosphate (2-methyl-S-ATP), a specific P2y receptor agonist, has no effect upon PtdIns(4,5)P2 hydrolysis in the absence of guanine nucleotides, but greatly enhances both the potency and efficacy of PIC activation by guanine nucleotides such as GTP gamma S. GTP gamma S alone stimulates PIC activity only after a prolonged time-lag; the effect of increasing doses of 2-methyl-S-ATP is progressively to shorten this lag phase. These results suggest that the mechanism of G-protein activation involves acceleration of a nucleotide exchange reaction as has been demonstrated for the activation of adenylate cyclase in the same membrane preparation. As well as contributing valuable information on the substrate specificity of PIC and its mode of regulation by hormones, turkey erythrocytes provide a plentiful source of plasma membranes and may be useful for purification of the appropriate G-protein and PIC activities.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0962-8436
pubmed:author
pubmed:issnType
Print
pubmed:day
26
pubmed:volume
320
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
267-80
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1988
pubmed:articleTitle
Receptor and G-protein-dependent regulation of turkey erythrocyte phosphoinositidase C.
pubmed:affiliation
Department of Cellular Pharmacology, Smith Kline & French Research Limited, Welwyn, Hertfordshire, U.K.
pubmed:publicationType
Journal Article, Review