title: Posttranscriptional regulation of the proximal tubule NaPi-II transporter in response to PTH and dietary P(i).
abstract: The rate of proximal tubular reabsorption of phosphate (P(i)) is a major determinant of P(i) homeostasis. Deviations of the extracellular concentration of P(i) are corrected by many factors that control the activity of Na-P(i) cotransport across the apical membrane. In this review, we describe the regulation of proximal tubule P(i) reabsorption via one particular Na-P(i) cotransporter (the type IIa cotransporter) by parathyroid hormone (PTH) and dietary phosphate intake. Available data indicate that both factors determine the net amount of type IIa protein residing in the apical membrane. The resulting change in transport capacity is a function of both the rate of cotransporter insertion and internalization. The latter process is most likely regulated by PTH and dietary P(i) and is considered irreversible since internalized type IIa Na-P(i) cotransporters are subsequently routed to the lysosomes for degradation.
authors.affiliation: Institute of Physiology, University of Zurich, CH-8057 Zurich, Switzerland.
authors.forename: H
authors.initials: H
authors.lastname: Murer
authors.forename: I
authors.initials: I
authors.lastname: Forster
authors.forename: N
authors.initials: N
authors.lastname: Hernando
authors.forename: G
authors.initials: G
authors.lastname: Lambert
authors.forename: M
authors.initials: M
authors.lastname: Traebert
authors.forename: J
authors.initials: J
authors.lastname: Biber
mesh_terms: D000042:Absorption; D000595:Amino Acid Sequence / Q000235:genetics; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology*; D004032:Diet; D007687:Kidney Tubules, Proximal / Q000378:metabolism*; D008969:Molecular Sequence Data; D010281:Parathyroid Hormone / Q000502:physiology*; D010710:Phosphates / Q000008:administration & dosage* / Q000378:metabolism / Q000494:pharmacology; D011499:Protein Processing, Post-Translational; D050608:Sodium-Phosphate Cotransporter Proteins; D027981:Symporters
chemical_list: D002352:Carrier Proteins; D010281:Parathyroid Hormone; D010710:Phosphates; D050608:Sodium-Phosphate Cotransporter Proteins; D027981:Symporters