title: A TRP homolog in Saccharomyces cerevisiae forms an intracellular Ca(2+)-permeable channel in the yeast vacuolar membrane.
abstract: The molecular identification of ion channels in internal membranes has made scant progress compared with the study of plasma membrane ion channels. We investigated a prominent voltage-dependent, cation-selective, and calcium-activated vacuolar ion conductance of 320 pS (yeast vacuolar conductance, YVC1) in Saccharomyces cerevisiae. Here we report on a gene, the deduced product of which possesses significant homology to the ion channel of the transient receptor potential (TRP) family. By using a combination of gene deletion and re-expression with direct patch clamping of the yeast vacuolar membrane, we show that this yeast TRP-like gene is necessary for the YVC1 conductance. In physiological conditions, tens of micromolar cytoplasmic Ca(2+) activates the YVC1 current carried by cations including Ca(2+) across the vacuolar membrane. Immunodetection of a tagged YVC1 gene product indicates that YVC1 is primarily localized in the vacuole and not other intracellular membranes. Thus we have identified the YVC1 vacuolar/lysosomal cation-channel gene. This report has implications for the function of TRP channels in other organisms and the possible molecular identification of vacuolar/lysosomal ion channels in other eukaryotes.
authors: Laboratory of Molecular Biology, University of Wisconsin, Madison, WI 53706, USA.
authors: C P
authors: CP
authors: Palmer
authors: X L
authors: XL
authors: Zhou
authors: J
authors: J
authors: Lin
authors: S H
authors: SH
authors: Loukin
authors: C
authors: C
authors: Kung
authors: Y
authors: Y
authors: Saimi
mesh_terms: D000595:Amino Acid Sequence; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000235:genetics* / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D007473:Ion Channels / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D050052:TRPC Cation Channels
chemical_list: D015220:Calcium Channels; D005656:Fungal Proteins; D007473:Ion Channels; D050052:TRPC Cation Channels; D002118:Calcium