Coexpression of a Ca(v)1.2 protein lacking an N-terminus and the first domain specifically suppresses L-type calcium channel activity.
L-type Ca(2) channels play a critical role in many types of cells, including nerve, muscle and endocrine cells. The most popular and effective tools for analyzing the roles of L-type calcium channels (L-channels) are specific antagonists such as dihydropyrigines. With these drugs however, it is difficult to target specific cells. One solution is to develop a genetically targetable inhibitor coded by DNA. As a candidate for such an inhibitor, a dominant negative mutant of Ca(v)1.2 was designed by mimicking an ascidian 3-domain-type alpha1 subunit (that inhibits the full-length subunit's current). The 3-domain-type Ca(v)1.2 subunit significantly inhibited wild-type Ca(v)1.2 current, but not other ionic currents such as Ca(v)2.1 and Na(v) channels in Xenopus oocyte expression systems. Western blot analysis showed that the expression of the wild-type protein into the plasma membrane was significantly suppressed on coexpression with the truncated protein. These findings support that an N-terminus-truncated mutant could serve as a specific genetically encoded inhibitor for L-channels.
Ebihara
Tatsuhiko
T
Molecular Neurophysiology Group, Neuroscience Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8566, Japan. t.ebihara@aist.go.jp
Komiya
Yuriko
Y
Izumi-Nakaseko
Hiroko
H
Adachi-Akahane
Satomi
S
Okabe
Shigeo
S
Okamura
Yasushi
Y
D000595:Amino Acid Sequence; D000818:Animals; D020746:Calcium Channels, L-Type / Q000737:chemistry / Q000378:metabolism*; D002460:Cell Line; D006224:Cricetinae; D008969:Molecular Sequence Data; D018408:Patch-Clamp Techniques; D017386:Sequence Homology, Amino Acid; D014981:Xenopus
D020746:Calcium Channels, L-Type; C419385:L-type calcium channel alpha(1C)