Multiple structural elements contribute to the slow kinetics of the Cav3.3 T-type channel.
Molecular cloning and expression studies established the existence of three T-type Ca(2+) channel (Ca(v)3) alpha(1) subunits: Ca(v)3.1 (alpha(1G)), Ca(v)3.2 (alpha(1H)), and Ca(v)3.3 (alpha(1I)). Although all three channels are low voltage-activated, they display considerable differences in their kinetics, with Ca(v)3.1 and Ca(v)3.2 channels activating and inactivating much faster than Ca(v)3.3 channels. The goal of the present study was to determine the structural elements that confer the distinctively slow kinetics of Ca(v)3.3 channels. To address this question, a series of chimeric channels between Ca(v)3.1 and Ca(v)3.3 channels were constructed and expressed in Xenopus oocytes. Kinetic analysis showed that the slow activation and inactivation kinetics of the Ca(v)3.3 channel were not completely abolished by substitution with any one portion of the Ca(v)3.1 channel. Likewise, the Ca(v)3.1 channel failed to acquire the slow kinetics by simply adopting one portion of the Ca(v)3.3 channel. These findings suggest that multiple structural elements contribute to the slow kinetics of Ca(v)3.3 channels.
Park
Jin-Yong
JY
Department of Life Science, Sogang University, Shinsu-dong, Seoul 121-742, Korea.
Kang
Ho-Won
HW
Jeong
Seong-Woo
SW
Lee
Jung-Ha
JH
D000818:Animals; D020747:Calcium Channels, T-Type / Q000737:chemistry* / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism; D004594:Electrophysiology; D007700:Kinetics; D026901:Membrane Transport Proteins; D009865:Oocytes / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D016133:Polymerase Chain Reaction; D017434:Protein Structure, Tertiary; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry; D013997:Time Factors; D014981:Xenopus
C469757:CACNA1I protein, human; D020747:Calcium Channels, T-Type; D018076:DNA, Complementary; D026901:Membrane Transport Proteins; D011994:Recombinant Proteins