Document Detail


Stimulation of fructose transport across the intestinal brush-border membrane by PMA is mediated by GLUT2 and dynamically regulated by protein kinase C.
MedLine Citation:
PMID:  10926838     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Perfusion of rat jejunum in vitro with PMA increased fructose transport by 70% compared with control values and was blocked by the protein kinase C (PKC) inhibitor chelerythrine. The brush-border membrane contained both the fructose transporters GLUT5 and GLUT2; the presence of the latter was confirmed by luminal biotinylation. PMA increased the GLUT2 level 4-fold within minutes, so that the level was comparable with that of the basolateral membrane, but had no effect on GLUT5 level. GLUT2 was functional, accessible to luminal fructose and could be inhibited selectively by phloretin to permit determination of GLUT2- and GLUT5-mediated transport components. The 4-fold increase in GLUT2 level induced by PMA was matched by a 4-fold increase in GLUT2-mediated transport: there was a compensatory fall in the GLUT5-mediated rate. The pattern of dynamic trafficking was seen only for GLUT2, not GLUT5 or SGLT1, implying that GLUT2 trafficks to the brush-border membrane by a different pathway. Trafficking of GLUT2 to the brush-border membrane correlated with activation of PKC betaII, implying that this isoenzyme is likely to control trafficking. Since PKC is activated by endogenous hormones, GLUT2 levels in vivo are 3-4-fold those in vitro; moreover, because PKC is inactivated as soon as intestine is excised, GLUT2 is lost from the brush-border within minutes in vitro. It is therefore difficult to detect GLUT2 in most in vitro preparations and its role in intestinal sugar absorption across the brush-border membrane has accordingly been overlooked.
Authors:
P A Helliwell; M Richardson; J Affleck; G L Kellett
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Biochemical journal     Volume:  350 Pt 1     ISSN:  0264-6021     ISO Abbreviation:  Biochem. J.     Publication Date:  2000 Aug 
Date Detail:
Created Date:  2001-01-02     Completed Date:  2001-01-11     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  2984726R     Medline TA:  Biochem J     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  149-54     Citation Subset:  IM    
Affiliation:
Department of Biology, University of York, PO Box 373, York YO10 5YW, U.K.
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MeSH Terms
Descriptor/Qualifier:
Animals
Biological Transport
Fructose / metabolism*
Glucose Transporter Type 2
Jejunum / drug effects*,  enzymology,  metabolism
Male
Microvilli / drug effects,  enzymology,  metabolism
Monosaccharide Transport Proteins / metabolism*
Protein Kinase C / metabolism*
Rats
Rats, Wistar
Tetradecanoylphorbol Acetate / pharmacology*
Chemical
Reg. No./Substance:
0/Glucose Transporter Type 2; 0/Monosaccharide Transport Proteins; 16561-29-8/Tetradecanoylphorbol Acetate; 30237-26-4/Fructose; EC 2.7.11.13/Protein Kinase C
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