cis,cis-cyclohexane 1,3,5-triol polyphosphates release calcium from Neurospora crassa via an unspecific Ins 1,4,5-P3...

We investigated the effects of new inositol 1,4,5-trisphosphate analogues on the release of Ca2+ from isolated vacuoles of Neurospora crassa. Tri-O-butyryl-inositol 1,4,5-trisphosphate and a set of cis,cis-cyclohexane 1,3,5-triol bis-(CHT-P2) and trisphosphates (CHT-P3) gave an increase in free Ca2+ as measured directly with fura-2, a Ca2(+)-chelator. However, inositol 1,4-bisphosphate, 6-O-palmitoyl-inositol 4,5-bisphosphate and trans-cyclohexane 1,2-diol bisphosphate (trans CHD-P2) did not induce Ca2(+)-release. These results suggest that the 1,5-bisphosphate position in inositol 1,4,5-trisphosphate (Ins 1,4,5-P3) is the only essential arrangement for receptor binding to vacuoles of Neurospora crassa. The structures of these analogues are discussed on the basis of a general concept for the design of new Ins 1,4,5-P3 analogues.