INIMEC - CONICET   05467
INSTITUTO DE INVESTIGACION MEDICA MERCEDES Y MARTIN FERREYRA
Unidad Ejecutora - UE
artículos
Título:
"In bovine heart Na+/Ca2+ exchanger maximal Ca2+i affinity requiers simultaneously high pHi and PtdIns-4,5-P2 binding to the carrier”
Autor/es:
VELIA POSADA, LUIS BEAUGÉ AND GRACIELA ELSO DE BERBERIÁN.
Revista:
ANNALS OF THE NEW YORK ACADEMY OF SCIENCES.
Editorial:
N.Y.Acad.Sci
Referencias:
Lugar: Los Angeles, California, USA; Año: 2006 vol. 109
ISSN:
0077-8923
Resumen:
In bovine heart Na+/Ca2+ exchanger maximal Ca2+i affinity requires simultaneous de-protonation and PtdIns-4,5-P2 binding to the carrier   Velia Posada* , Luis Beaugé* and Graciela Berberián* * Laboratorio de Biofísica, Instituto de Investigación Médica  “Mercedes y Martín Ferreyra”. (INIMEC-CONICET), Casilla de Correo 389, 5000,  Córdoba, Argentina. Abstract Na+i-dependent Ca2+- uptake, Na+-dependent Ca2+- release and PtdIns-4,5-P2 binding to NCX1 as a function of extra-vesicular (intracellular) [Ca2+] were. Alkalinization increases Ca 2+i affinity and PtdIns-4,5-P2 bound to NCX1; these effects are abolished by pre-treatment with  PtdIns-PLC but are insensitive to MgATP.  Acidification reduces Ca 2+i affinity. MgATP reverts it only partially despite the fact tha the PtdIns-4,5-P2 bound to NCX1 reaches the same levels as at pH 7.8.  Extra-vesicular Na+-stimulated and Ca2+-dependent Ca2+efflux indicate the Ca2+ regulatory site is involved.  Therefore, to display maximal affinity to Ca 2+i, PtdIns -4,5-P2 binding and de-protonation of NCX1 are simultaneously need.   Key words: Na+/Ca2+ exchange; NCX1; pH and PtdIns-4,5-P2 modulation; Ca2+i affinity