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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6106
pubmed:dateCreated
1987-4-1
pubmed:abstractText
Phosphatidylinositol (PtdIns), the most abundant phosphoinositide, is the precursor of phosphatidylinositol 4-monophosphate which is converted to phosphatidylinositol 4,5-bisphosphate, the lipid hydrolysed as an early step in signal transduction by many stimuli. It is generally thought that a single enzyme in the endoplasmic reticulum, PtdIns synthase (CDP-diglyceride:myoinositol 3-phosphatidyltransferase, EC 2.7.8.11), is responsible for PtdIns synthesis and that newly synthesized PtdIns is transported to the plasma membrane by exchange proteins. Several investigators have proposed that there are two functionally distinct pools of PtdIns, one responsive to stimulation and the other not, and that the stimulus-responsive pool may be synthesized at a different site within the cell, perhaps within the plasma membrane. Indeed, it was suggested that there is PtdIns synthase activity in plasma membrane isolated from rat liver. GH3 rat pituitary tumour cells are an excellent model system to study stimulation of phosphoinositide metabolism by thyrotropin-releasing hormone (TRH). Conversion of PtdIns to polyphosphoinositides and TRH (and GTP)-activated phosphoinositide hydrolysis are known to occur in plasma membrane isolated from GH3 cells. Here we report that PtdIns synthase activity in the plasma membrane of GH3 cells is distinct from that present in the endoplasmic reticulum. The plasma membrane PtdIns synthase may be responsible for a portion of PtdIns re-synthesis that occurs during cell stimulation.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0028-0836
pubmed:author
pubmed:issnType
Print
pubmed:volume
325
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
726-8
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:articleTitle
Independent phosphatidylinositol synthesis in pituitary plasma membrane and endoplasmic reticulum.
pubmed:publicationType
Journal Article