Micro-injection of inositol 1,3,4,5-tetrakisphosphate activates sea urchin eggs by a mechanism dependent on external Ca2+.
Micro-injection of submicromolar concentrations of inositol 1,3,4,5-tetrakisphosphate caused a raising of the fertilization envelope in eggs of the sea urchin Lytechinus variegatus. This effect was dependent both on the presence of extracellular Ca2+ and on co-injection with a Ca2+-mobilizing compound, inositol 2,4,5-trisphosphate. Inositol 1,3,4,5-tetrakisphosphate was the most potent compound tested in this assay; removal of the 3- or 5-phosphates or randomization of the phosphates in the inositol ring decreased its potency. These results show that inositol 1,3,4,5-tetrakisphosphate is an intracellular second messenger, and suggest that its function is to control cellular Ca2+ homoeostasis at the plasma membrane.
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D007295:Inositol Phosphates / Q000494:pharmacology*; D008845:Microinjections; D010063:Ovum / Q000187:drug effects / Q000378:metabolism*; D012617:Sea Urchins; D013403:Sugar Phosphates / Q000494:pharmacology*
D007295:Inositol Phosphates; D013403:Sugar Phosphates; C081655:inositol-1,3,4,5-tetrakisphosphate; D002118:Calcium