Document Detail


Differential expression of a C-terminal splice variant of phosphatidylinositol transfer protein beta lacking the constitutive-phosphorylated Ser262 that localizes to the Golgi compartment.
MedLine Citation:
PMID:  16780419     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Mammalian PITPbeta (phosphatidylinositol transfer protein beta) is a 272-amino-acid polypeptide capable of transferring PtdIns, PtdCho and SM (sphingomyelin) between membrane bilayers. It has been reported that Ser262 present in the C-terminus of PITPbeta is constitutively phosphorylated and determines Golgi localization. We provide evidence for the expression of an sp (splice) variant of PITPbeta (PITPbeta-sp2) where the C-terminal 15 amino acids of PITPbeta-sp1 are replaced by an alternative C-terminus of 16 amino acids. PITPbeta-sp1 is the product of the first 11 exons, whereas PITPbeta-sp2 is a product of the first 10 exons followed by the twelfth exon--exon 11 being 'skipped'. Both splice variants are capable of PtdIns and PtdCho transfer, with PITPbeta-sp2 being unable to transport SM. PITPbeta is ubiquitously expressed, with the highest amounts of PITPbeta found in HL60 cells and in rat liver; HL60 cells express only PITPbeta-sp1, whereas rat liver expresses both sp variants in similar amounts. In both cell types, PITPbeta-sp1 is constitutively phosphorylated and both the PtdIns and PtdCho forms of PITPbeta-sp1 are present. In contrast, PITPbeta-sp2 lacks the constitutively phosphorylated Ser262 (replaced with glutamine). Nonetheless, both PITPbeta variants localize to the Golgi and, moreover, dephosphorylation of Ser262 of PITPbeta-sp1 does not affect its Golgi localization. The presence of PITPbeta sp variants adds an extra level of proteome complexity and, in rat liver, the single gene for PITPbeta gives rise to seven distinct protein species that can be resolved on the basis of their charge differences.
Authors:
Clive P Morgan; Victoria Allen-Baume; Marko Radulovic; Michelle Li; Alison Skippen; Shamshad Cockcroft
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Biochemical journal     Volume:  398     ISSN:  1470-8728     ISO Abbreviation:  Biochem. J.     Publication Date:  2006 Sep 
Date Detail:
Created Date:  2006-08-23     Completed Date:  2006-09-20     Revised Date:  2013-06-07    
Medline Journal Info:
Nlm Unique ID:  2984726R     Medline TA:  Biochem J     Country:  England    
Other Details:
Languages:  eng     Pagination:  411-21     Citation Subset:  IM    
Affiliation:
Lipid Signalling Group, Department of Physiology, University College London, 21 University Street, Rockefeller Building, London WC1E 6JJ, UK.
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MeSH Terms
Descriptor/Qualifier:
Alternative Splicing / physiology*
Amino Acid Sequence
Amino Acid Substitution
Animals
COS Cells
Cercopithecus aethiops
Cytosol
Gene Expression Regulation
Golgi Apparatus / metabolism*
HL-60 Cells
Humans
Liver / cytology
Molecular Sequence Data
Phospholipid Transfer Proteins / metabolism*
Phosphorylation
Protein Binding
Protein Transport
Rats
Grant Support
ID/Acronym/Agency:
//Wellcome Trust
Chemical
Reg. No./Substance:
0/Phospholipid Transfer Proteins
Comments/Corrections

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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