Regulation of Na(+)-coupled glucose transport in LLC-PK1 cells. Message stabilization induced by cyclic AMP elevation is accompanied by binding of a M(r) = 48,000 protein to a uridine-rich domain in the 3'-untranslated region.
In an exploration of the molecular basis of cyclic AMP-induced stabilization of Na+/glucose cotransporter mRNA (SGLT1 isoform) accompanying cell differentiation in the pig kidney cell line LLC-PK1, we have identified a 48-kDa cytoplasmic protein factor, designated SG-URBP, which specifically binds a 120-nucleotide sequence within the 3'-untranslated region of the SGLT1 message. A 46-nucleotide uridine-rich element within this region appears necessary for specific binding, and the presence of the 3'-untranslated region is necessary for message stabilization by cyclic AMP. The binding activity of SG-URBP is up-regulated after cyclic AMP elevation and protein kinase A activation, whereas protein dephosphorylation either in vivo or in vitro is associated with loss of binding activity. The increase in SG-URBP binding activity correlates with an increase in the half-life of the SGLT1 message, suggesting a cause and effect relationship.
Peng
H
H
Department of Biochemistry & Molecular Biology, University of Texas Medical School, Houston 77225, USA.
Lever
J E
JE
D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004789:Enzyme Activation; D007668:Kidney / Q000378:metabolism; D018374:LLC-PK1 Cells; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins / Q000096:biosynthesis*; D015347:RNA Probes; D012333:RNA, Messenger / Q000096:biosynthesis / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis; D015183:Restriction Mapping; D013552:Swine; D014158:Transcription, Genetic; D014162:Transfection; D014529:Uridine
D009004:Monosaccharide Transport Proteins; D015347:RNA Probes; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D014529:Uridine