Modulation of renal type IIa Na+/Pi cotransporter kinetics by the arginine modifier phenylglyoxal.
J Membr Biol
; 187(2): 85-96, 2002 May 15.
Article
em En
| MEDLINE
| ID: mdl-12029367
ABSTRACT
The effects of the arginine-modifying reagent phenylglyoxal on the kinetics of the type IIa Na + /Pi cotransporter expressed in Xenopus, oocytes were studied by means of 32Pi uptake and electrophysiology. Phenylglyoxal incubation induced up to 60% loss of cotransport function but only marginally altered the Na+-leak. Substrate activation and pH dependency remained essentially unaltered, whereas the voltage dependency of Pi-induced change in electrogenic response was significantly reduced. Presteady-state charge movements were suppressed and the equilibrium charge distribution was shifted slightly towards hyperpolarizing potentials. Charge movements in the absence of external Na+ were also suppressed, which indicated that the empty-carrier kinetics were modified. These effects were incorporated into an ordered alternating access model for NaPi-IIa, whereby the arginine modification by phenylglyoxal was modeled as altered apparent electrical distances moved by mobile charges, together with a slower rate of translocation of the electroneutral, fully loaded carrier.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fenilglioxal
/
Arginina
/
Simportadores
/
Potenciais da Membrana
Tipo de estudo:
Diagnostic_studies
/
Prognostic_studies
Limite:
Animals
Idioma:
En
Revista:
J Membr Biol
Ano de publicação:
2002
Tipo de documento:
Article