Molecular identification of a eukaryotic, stretch-activated nonselective cation channel.
Calcium-permeable, stretch-activated nonselective cation (SA Cat) channels mediate cellular responses to mechanical stimuli. However, genes encoding such channels have not been identified in eukaryotes. The yeast MID1 gene product (Mid1) is required for calcium influx in the yeast Saccharomyces cerevisiae. Functional expression of Mid1 in Chinese hamster ovary cells conferred sensitivity to mechanical stress that resulted in increases in both calcium conductance and the concentration of cytosolic free calcium. These increases were dependent on the presence of extracellular calcium and were reduced by gadolinium, a blocker of SA Cat channels. Single-channel analyses with cell-attached patches revealed that Mid1 acts as a calcium-permeable, cation-selective stretch-activated channel with a conductance of 32 picosiemens at 150 millimolar cesium chloride in the pipette. Thus, Mid1 appears to be a eukaryotic, SA Cat channel.
Kanzaki
M
M
Laboratory of Cell Biology, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8510, Japan.
Nagasawa
M
M
Kojima
I
I
Sato
C
C
Naruse
K
K
Sokabe
M
M
Iida
H
H
D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002412:Cations / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002463:Cell Membrane Permeability; D002586:Cesium / Q000378:metabolism; D002712:Chlorides / Q000494:pharmacology; D006224:Cricetinae; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005682:Gadolinium / Q000494:pharmacology; D007473:Ion Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008564:Membrane Potentials; D008969:Molecular Sequence Data; D018408:Patch-Clamp Techniques; D011312:Pressure; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D013314:Stress, Mechanical; D014162:Transfection; D017967:Zinc Compounds / Q000494:pharmacology
D015220:Calcium Channels; D002412:Cations; D002712:Chlorides; D005656:Fungal Proteins; D007473:Ion Channels; C090463:MID1 protein, S cerevisiae; D008562:Membrane Glycoproteins; D029701:Saccharomyces cerevisiae Proteins; D017967:Zinc Compounds; D002586:Cesium; C016837:zinc chloride; D005682:Gadolinium; D002118:Calcium