TY - JOUR
T1 - Selective removal of alkaline phosphatase from renal brush-border membrane and sodium-dependent brush-border membrane transport
AU - Yusufi, A. N.K.
AU - Low, M. G.
AU - Turner, S. T.
AU - Dousa, T. P.
N1 - Copyright:
Copyright 2004 Elsevier B.V., All rights reserved.
PY - 1983
Y1 - 1983
N2 - Na+-gradient-dependent transport of phosphate (P(i), glucose, and proline was studied in renal brush-border membranes (BBM) from which alkaline phosphatase was released by treatment with phosphatidylinositol-specific phospholipase C. BBM were prepared from rabbit kidney cortex in the form of large brush-border membrane sheets (BBMS). Incubation of BBMS with bacterial phosphatidylinositol-specific phospholipase C resulted in selective release (up to 90%) of the alkaline phosphatase from BBM; in contrast, activities of leucine aminopeptidase, γ-glutamyltranspeptidase, and maltase were not affected. Polytron homogenization of BBMS leads to the formation of brush-border membrane vesicles (BBMV) capable of concentrative uptake of solutes. BBMS and BBMV were prepared from kidneys of rabbits fed either a high (1.2% P), low (0.07% P), or normal P diet. Enzymatic deletion of alkaline phosphatase from BBMV prepared from animals fed the low P diet resulted in a marked increase in Na+-gradient-dependent uptake of P(i). No such effect was observed in BBMV from animals fed the normal or high P diets. These experiments indicate that the presence of alkaline phosphatase in BBM is not required for Na+-gradient-dependent transport of P(i), glucose, and proline. Likewise, the adaptive increase in BBM transport of P(i) elicited in response to low dietary P intake does not depend on the presence of, or increase in, alkaline phosphatase activity. Our findings argue against a direct involvement of alkaline phosphatase in Na+-dependent P(i) transport across the renal BBM. It is not excluded, however, that alkaline phosphatase might play a role in the modulation of P(i) transport.
AB - Na+-gradient-dependent transport of phosphate (P(i), glucose, and proline was studied in renal brush-border membranes (BBM) from which alkaline phosphatase was released by treatment with phosphatidylinositol-specific phospholipase C. BBM were prepared from rabbit kidney cortex in the form of large brush-border membrane sheets (BBMS). Incubation of BBMS with bacterial phosphatidylinositol-specific phospholipase C resulted in selective release (up to 90%) of the alkaline phosphatase from BBM; in contrast, activities of leucine aminopeptidase, γ-glutamyltranspeptidase, and maltase were not affected. Polytron homogenization of BBMS leads to the formation of brush-border membrane vesicles (BBMV) capable of concentrative uptake of solutes. BBMS and BBMV were prepared from kidneys of rabbits fed either a high (1.2% P), low (0.07% P), or normal P diet. Enzymatic deletion of alkaline phosphatase from BBMV prepared from animals fed the low P diet resulted in a marked increase in Na+-gradient-dependent uptake of P(i). No such effect was observed in BBMV from animals fed the normal or high P diets. These experiments indicate that the presence of alkaline phosphatase in BBM is not required for Na+-gradient-dependent transport of P(i), glucose, and proline. Likewise, the adaptive increase in BBM transport of P(i) elicited in response to low dietary P intake does not depend on the presence of, or increase in, alkaline phosphatase activity. Our findings argue against a direct involvement of alkaline phosphatase in Na+-dependent P(i) transport across the renal BBM. It is not excluded, however, that alkaline phosphatase might play a role in the modulation of P(i) transport.
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M3 - Article
C2 - 6853540
AN - SCOPUS:0020519745
SN - 0021-9258
VL - 258
SP - 5695
EP - 5701
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 9
ER -