Inositol trisphosphate induces calcium release from Neurospora crassa vacuoles

Inositol 1,4,5-trisphosphate is known to release calcium ions from intracellular stores thought to be parts of endoplasmic reticulum in animal cells. In Neurospora crassa, however, inositol 1,4,5-trisphosphate acts on vacuoles stimulating a calcium efflux with a Km of 5.28 microM. The calcium release is inhibited effectively by dantrolene. These results were obtained by applying two independent methods, measuring calcium binding to fura-2 and loading vacuoles with 45Ca.