title: Apical and basolateral parathyroid hormone receptors in rat renal cortical membranes.
abstract: Brush border (BBM) and basolateral membranes (BLM) of rat renal cortical cells separated by free flow electrophoresis revealed two distinct peaks of BBM-specific leucine aminopeptidase and Na+/K(+)-ATPase for BLM. PTH/PTH-related protein (PTHrP) receptors were identified in BBM and BLM. Specific binding of 125 pM [125I]chicken [Tyr36]-PTHrP-(1-36)amide [chPTHrP-(1-36)] to individual fractions of membranes separated by free flow electrophoresis overlapped with the leucine aminopeptidase and Na+/K(+)-ATPase profiles. Binding to pooled BBM was 53 +/- 5% (mean +/- SEM) of that to BLM (P < 0.01). In BBM and BLM, half-maximal inhibition of binding was obtained with 0.4-0.9 nM chPTHrP-(1-36) and 0.2-0.6 nM rat PTH-(1-34). Guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S; 100 microM) lowered chPTHrP-(1-36) binding to 50% of control levels, and half-maximal inhibition of binding was obtained with 480 and 8 nM GTP gamma S in BBM and BLM, respectively. Cross-linking of the PTH/PTHrP receptors with [125I]chPTHrP-(1-36) modified with N-hydroxysuccinimidyl-4-azidobenzoate revealed indistinguishable doublets of 83 and 73 kilodaltons in both BBM and BLM. Adenylyl cyclase was stimulated 6- and 10-fold by chPTHrP-(1-36) and GTP gamma S, respectively, in BLM and 1.3- and 1.9-fold in BBM. In conclusion, PTH receptors were recognized in both the basolateral and brush border membranes. Different receptor coupling to G-proteins and minimal cAMP stimulation in BBM provide evidence for PTH/PTHrP receptor isotypes and/or different postreceptor activation in BBM and BLM.
authors.affiliation: Department of Orthopedic Surgery, University Hospital, Zurich, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Kaufmann
authors.forename: R
authors.initials: R
authors.lastname: Muff
authors.forename: B
authors.initials: B
authors.lastname: Stieger
authors.forename: J
authors.initials: J
authors.lastname: Biber
authors.forename: H
authors.initials: H
authors.lastname: Murer
authors.forename: J A
authors.initials: JA
authors.lastname: Fischer
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D001485:Basement Membrane / Q000737:chemistry; D019204:GTP-Binding Proteins / Q000032:analysis; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D007672:Kidney Cortex / Q000737:chemistry* / Q000648:ultrastructure; D008297:Male; D008871:Microvilli / Q000737:chemistry; D044162:Parathyroid Hormone-Related Protein; D010446:Peptide Fragments / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D018016:Receptors, Parathyroid Hormone / Q000032:analysis*
chemical_list: D044162:Parathyroid Hormone-Related Protein; D010446:Peptide Fragments; D011506:Proteins; D018016:Receptors, Parathyroid Hormone; C079957:parathyroid hormone-related peptide (1-36); D016244:Guanosine 5'-O-(3-Thiotriphosphate); D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases