RGD Reference Report - Sterol carrier protein-2 functions in phosphatidylinositol transfer and signaling. - Rat Genome Database

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Sterol carrier protein-2 functions in phosphatidylinositol transfer and signaling.

Authors: Schroeder, F  Zhou, M  Swaggerty, CL  Atshaves, BP  Petrescu, AD  Storey, SM  Martin, GG  Huang, H  Helmkamp, GM  Ball, JM 
Citation: Schroeder F, etal., Biochemistry. 2003 Mar 25;42(11):3189-202.
RGD ID: 8553638
Pubmed: PMID:12641450   (View Abstract at PubMed)
DOI: DOI:10.1021/bi026904+   (Journal Full-text)

Over 20 years ago, it was reported that liver cytosol contains at least two distinct proteins that transfer phosphatidylinositol in vitro, phosphatidylinositol transfer protein (PITP) and a pH 5.1 supernatant fraction containing sterol carrier protein-2 (SCP-2). In contrast to PITP, there has been minimal progress on the structural and functional significance of SCP-2 in phosphatidylinositol transport. As shown herein, highly purified, recombinant SCP-2 stimulated up to 13-fold the rapid (s) transfer of radiolabeled phosphatidylinositol (PI) from microsomal donor membranes to highly curved acceptor membranes. SCP-2 bound to microsomes in vitro and overexpression of SCP-2 in transfected L-cells resulted in the following: (i) redistribution of phosphatidylinositols from intracellular membranes (mitochondria and microsomes) to the plasma membrane; (ii) enhancement of insulin-mediated inositol-triphosphate production; and (iii) 5.5-fold down regulation of PITP. Like PITP, SCP-2 binds two ligands required for vesicle budding from the Golgi, PI, and fatty acyl CoA. Double immunolabeling confocal microscopy showed SCP-2 significantly colocalized with caveolin-1 in the cytoplasm (punctate) and plasma membrane of SCP-2 overexpressing hepatoma cells (72%), HT-29 cells (58%), and SCP-2 overexpressing L-cells (37%). Taken together, these data show for the first time that SCP-2 plays a hitherto unrecognized role in intracellular phosphatidylinositol transfer, distribution, and signaling.

Gene Ontology Annotations    Click to see Annotation Detail View

Biological Process
TermQualifierEvidenceWithReferenceNotesSourceOriginal Reference(s)
phospholipid transport involved_inIDA 8553638PMID:12641450UniProt 

Molecular Function
TermQualifierEvidenceWithReferenceNotesSourceOriginal Reference(s)
fatty-acyl-CoA binding enablesIDA 8553638PMID:12641450UniProt 
phosphatidylinositol binding enablesIDA 8553638PMID:12641450UniProt 
phosphatidylinositol transfer activity enablesIDA 8553638PMID:12641450UniProt 
stearic acid binding enablesIDA 8553638PMID:12641450UniProt 

Objects Annotated

Genes (Rattus norvegicus)
Pitpna  (phosphatidylinositol transfer protein, alpha)

Additional Information