Comparative analysis of the ontogeny of a sodium-dependent bile acid transporter in rat kidney and ileum.
An apical sodium-dependent bile acid transporter (ASBT) has recently been cloned and characterized in the rat ileum. Northern and Western blotting revealed both the ASBT mRNA and protein in rat kidney. The coding sequence of the kidney transcript was found to be identical to the previously cloned ileal ASBT. Indirect immunofluorescence studies localized the ASBT protein to the apical membrane of the renal proximal convoluted tubule. Kinetic analysis of sodium-dependent taurocholate uptake using membrane vesicles revealed a similar Michaelis-Menten constant value for taurocholate in the kidney and intestine. ASBT protein and function were present in the kidney but not the ileum from 7-day-old rats. On postnatal day 7, there was a sevenfold increase in ASBT steady-state mRNA levels in the kidney relative to the ileum, yet nuclear run-on assays revealed that the nascent transcription rates at this age were virtually the same. This suggests that the difference in the neonatal expression of the ASBT gene in the kidney and ileum may be in part due to differences in mRNA stability.
Christie
D M
DM
Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
Dawson
P A
PA
Thevananther
S
S
Shneider
B L
BL
D000375:Aging / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development / Q000378:metabolism*; D001483:Base Sequence; D001647:Bile Acids and Salts / Q000378:metabolism; D001692:Biological Transport; D015152:Blotting, Northern; D015153:Blotting, Western; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D004247:DNA / Q000235:genetics; D019084:Fluorescent Antibody Technique, Indirect; D007082:Ileum / Q000254:growth & development / Q000378:metabolism*; D007668:Kidney / Q000254:growth & development / Q000378:metabolism*; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes / Q000235:genetics; D029363:Organic Anion Transporters, Sodium-Dependent; D051381:Rats; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000378:metabolism; D027981:Symporters; D014158:Transcription, Genetic
D001647:Bile Acids and Salts; D002352:Carrier Proteins; D015345:Oligonucleotide Probes; D029363:Organic Anion Transporters, Sodium-Dependent; D027981:Symporters; C071908:sodium-bile acid cotransporter; D004247:DNA; D012964:Sodium