Inositol 1,4,5-trisphosphate releases Ca super(2+) from vacuolar membrane vesicles of Saccharomyces cerevisiae

• Published in: FEBS letters 1993-01, Vol.323 (1-2), p.113-118
• Main Authors: Belde, PJM, Vossen, J H, Borst-Pauwels, GWFH, Theuvenet, APR
• Format: Article
• Language: English
• Subjects: Saccharomyces cerevisiae
• ISSN: 0014-5793

Inositol 1,4,5-trisphosphate (IP sub(3)) induces a release of Ca super(2+) from vacuolar membrane vesicles of Saccharomyces cerevisiae. The amount released is dependent on IP sub(3) concentration (concentration for half maximal effect, K sub(m, apparent) = 0.4 mu M). Myo-inositol, and inositol 1,4-bisphosphate up to 50 mu M have no effect on Ca super(2+) levels in the vesicles. The IP sub(3)-induced Ca super(2+) release is blocked by dantrolene and 8-(N,N-diethylamino)-octyl 3,4,5-trimethoxybenzoate-HCl (TMB-8), which are known to block Ca super(2+) release from Ca super(2+) stores in animal cells. IP sub(3)-induced release of Ca super(2+) also occurs when Ca super(2+) is accumulated by means of an artificial pH gradient, indicating that the effect of IP sub(3) is not due to an effect on the vacuolar H super(+)-ATPase. The IP sub(3)-induced Ca super(2+) release is not accompanied by a change in the pH gradient, which indicates that it is not due to a reversal of the Ca super(2+)/nH super(+) antiport or to a decrease in Delta pH by IP sub(3). The present results suggest that IP sub(3) may act as a second messenger in the mobilization of Ca super(2+) in yeast cells. As in plant cells, the vacuolar membrane of yeast seems to contain a Ca super(2+) channel, which can be opened by IP sub(3).