Inositol 1,4,5-triphosphate induces calcium release from a non- mitochondrial pool in amoebae of Dictyostelium.
Evidence is presented for two distinct CA2+ pools in amoebae of Dictyostelium discoideum. One pool, presumably mitochondrial, was sensitive to the mitochondrial inhibitors oligomycin and dinitrophenol and showed an affinity for Ca2+ in the micro M concentration range. The other Ca2+ pool, which was insensitive to these inhibitors, was of lower capacity but had higher affinity (in the nM range). Inositol 1,4,5-trisphosphate (5 micro M) added to saponin-permeabilized amoebae induced a rapid release of Ca2+ from the latter pool but had no effect on the presumed mitochondrial pool. Controls using addition of inositol 1,4-bisphosphate (the hydrolytic product of IP3) induced no such CA2+ release. The results provide strong support for the involvement of IP3 in signal transmission during chemotaxis of D. discoideum.
D000199:Actins / Q000502:physiology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002451:Cell Compartmentation; D002463:Cell Membrane Permeability; D006152:Cyclic GMP / Q000502:physiology; D004023:Dictyostelium / Q000166:cytology; D004721:Endoplasmic Reticulum / Q000378:metabolism; D015544:Inositol 1,4,5-Trisphosphate; D007295:Inositol Phosphates / Q000494:pharmacology*; D008928:Mitochondria / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000502:physiology; D013403:Sugar Phosphates / Q000494:pharmacology*
D000199:Actins; D007295:Inositol Phosphates; D011956:Receptors, Cell Surface; D013403:Sugar Phosphates; D015544:Inositol 1,4,5-Trisphosphate; D000255:Adenosine Triphosphate; D006152:Cyclic GMP; D002118:Calcium