Characterization of a novel intracellular sphingolipid-gated Ca(2+)-permeable channel from rat basophilic leukemia cells.
Sphingolipids stimulate the release of Ca2+ from intracellular stores. However, the mechanism by which this process occurs has not been characterized. Through single-channel recording from microsomes incorporated into planar lipid bilayers, we describe a novel channel that gates Ba2+ in response to sphingosylphosphorylcholine. The channel is both ligand-gated and voltage-modulated. Maximal open probability is observed between -10 and -20 mV and has a relatively high conductance (160 picosiemens with 53 mM Ba2+). We also observe that Ca2+ efflux from permeabilized rat basophilic leukemia cells is not antagonized by heparin, La3+, Ni2+, nifedipine, or omega-conotoxin GVIa. The sphingolipid-gated Ca(2+)-permeable channel is therefore a new member of the Ca(2+)-permeable, ligand-gated channel family.
Kindman
L A
LA
Division of Cardiovascular Medicine, Duke University Medical Center, Durham, North Carolina 27710.
Kim
S
S
McDonald
T V
TV
Gardner
P
P
D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000378:metabolism*; D015640:Ion Channel Gating; D015471:Leukemia, Basophilic, Acute; D008051:Lipid Bilayers; D051381:Rats; D013107:Sphingolipids / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D008051:Lipid Bilayers; D013107:Sphingolipids