Inositol 1,3,4,5-tetrakisphosphate-gated channels interact with inositol 1,4,5-trisphosphate-gated channels in olfactory receptor neurons.
Inositol 1,4,5-trisphosphate [InsP3(1,4,5)] is a major second messenger regulating Ca2+ signaling in excitable and nonexcitable cells. InsP3(1,4,5) is extensively metabolized through a network of phosphorylation and dephosphorylation steps to products with potential second messenger function. Inositol 1,3,4,5-tetrakisphosphate [InsP4(1,3,4,5)], the direct metabolite of InsP3(1,4,5), has also been associated with Ca2+ signaling, but whether InsP4(1,3,4,5) acts in combination with InsP3(1,4,5) or whether it regulates Ca2+ signaling directly and independently is unclear, particularly in neurons. We report that olfactory receptor neurons in the lobster (Panulirus argus) express an InsP4(1,3,4,5) receptor in the plasma membrane that is a functional channel. The channel differs in conductance, kinetics, and voltage sensitivity from two plasma membrane InsP3(1,4,5)-gated channels previously reported in these neurons. In close spatial proximity, the InsP4(1,3,4,5)-and InsP3(1,4,5)-gated channels interact reciprocally to alter the channels' open probabilities in what may be a novel mechanism for regulating Ca2+ entry in neurons.
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Whitney Laboratory, University of Florida, St. Augustine 32086.
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D000818:Animals; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D004558:Electric Stimulation; D015544:Inositol 1,4,5-Trisphosphate / Q000494:pharmacology*; D007295:Inositol Phosphates / Q000494:pharmacology*; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology*; D008121:Nephropidae; D018034:Olfactory Receptor Neurons / Q000502:physiology*; D015290:Second Messenger Systems
D015220:Calcium Channels; D007295:Inositol Phosphates; C081655:inositol-1,3,4,5-tetrakisphosphate; D015544:Inositol 1,4,5-Trisphosphate