Abstract
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.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 5695-5701 |
| Number of pages | 7 |
| Journal | Journal of Biological Chemistry |
| Volume | 258 |
| Issue number | 9 |
| State | Published - 1983 |
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ASJC Scopus subject areas
- Biochemistry
Cite this
Selective removal of alkaline phosphatase from renal brush-border membrane and sodium-dependent brush-border membrane transport. / Yusufi, A. N K; Low, M. G.; Turner, Stephen T; Dousa, T. P.
In: Journal of Biological Chemistry, Vol. 258, No. 9, 1983, p. 5695-5701.Research output: Contribution to journal › Article
}
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, Stephen T
AU - Dousa, T. P.
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
VL - 258
SP - 5695
EP - 5701
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 9
ER -