Endogenous TRPM4-like channel in Chinese hamster ovary (CHO) cells.
Chinese hamster ovary (CHO) cells used in many transfection studies have been found to endogenously express channels permeable to monovalent cations, but not to divalent cations. In the presence of intracellular Ca(2+), 23-pS channel with a linear current-voltage (I-V) relationship could be frequently observed in inside-out patches but not in cell-attached patches. The open probability was voltage-dependent, which is higher at positive potentials. The channel was dose-dependently activated by relatively high level of Ca(2+) (EC(50)=1.04+/-0.08 mM), and sensitively inhibited by 100 microM ATP, ADP, AMP, and 1mM spermine. However, ruthenium red (2 microM) had no effect. Reverse transcript polymerase chain reaction (RT-PCR) supported the presence of mRNA encoding TRPM4b channel protein. Western blot assay finally confirmed the presence of this channel protein in membrane fraction of CHO cells. These results provide evidence that CHO cells express an endogenous TRPM4b-like channel, and thereby can be used as a tool to study de novo regulation/modulation of TRPM4 channel.
Yarishkin
Oleg V
OV
Department of Physiology, Institute of Health Sciences, and Medical Research Center for Neural Dysfunction, Gyeongsang National University School of Medicine, 90 Chilam, Jinju 660-751, Republic of Korea.
Hwang
Eun-Mi
EM
Park
Jae-Yong
JY
Kang
Dawon
D
Han
Jaehee
J
Hong
Seong-Geun
SG
D000818:Animals; D016466:CHO Cells / Q000378:metabolism; D006224:Cricetinae; D003412:Cricetulus; D015640:Ion Channel Gating / Q000502:physiology*; D020033:Protein Isoforms / Q000378:metabolism; D050053:TRPM Cation Channels / Q000378:metabolism*
D020033:Protein Isoforms; D050053:TRPM Cation Channels; C437888:TRPM4 protein, human