STIMULATION OF THE YEAST MITOCHONDRIAL CALCIUM UNIPORTER BY HYPOTONICITY AND BY RUTHENIUM-RED

The Ca2+ uptake by mitochondria from the yeast Endomyces magnusii has earlier been found to be driven by the membrane potential and to be st imulated by; spermine, it thus functions in a similar fashion as the a nimal mitochondrial calcium uniporter. Here, it is shown that the upta ke is stimulated, i.e., Ca2+ can be accumulated from lower [Ca2+], und er hypotonic conditions. Ruthenium Red, an inhibitor of the animal uni porter, under certain conditions, stimulates the yeast uniporter. The mechanism of the stimulation by hypotonicity and Ruthenium Red is disc ussed. (C) 1998 Elsevier Science B.V.