Endocytic vesicles contain a calmodulin-activated Ca2+ pump that mediates the inhibition of acidification by calcium.
Endocytic vesicles isolated from rabbit reticulocytes contained an intrinsic Ca2(+)-pump activity that was dependent on ATP, activated by calmodulin and inhibited by vanadate. 45Ca2+ uptake and acidification studies indicated that acidification of the endocytic vesicles inversely correlated with the Ca2(+)-pump activity. Acidification was inhibited by externally added Ca2+ and calmodulin and activated by vanadate and EGTA. It is suggested that intravesicular Ca2+ can act as a modulator of endocytic vesicle acidification.
Núñez
M T
MT
Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago.
Gaete
V
V
Escobar
A
A
D000818:Animals; D001693:Biological Transport, Active; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D002147:Calmodulin / Q000494:pharmacology*; D004533:Egtazic Acid / Q000494:pharmacology; D004705:Endocytosis; D006863:Hydrogen-Ion Concentration; D011817:Rabbits; D012156:Reticulocytes / Q000187:drug effects / Q000378:metabolism*; D014638:Vanadates / Q000494:pharmacology
D015220:Calcium Channels; D002147:Calmodulin; D014638:Vanadates; D004533:Egtazic Acid