Tarantula toxin ProTx-I differentiates between human T-type voltage-gated Ca2+ Channels Cav3.1 and Cav3.2.
ProTx-I peptide, a venom toxin of the tarantula Thrixopelma pruriens, has been reported to interact with voltage-gated ion channels. ProTx-I reduced Ba(2+) currents through recombinant human T-type voltage-gated Ca(2+) channels, Ca(v)3.1 (hCa(v)3.1), with roughly 160-fold more potency than through hCa(v)3.2 channels. Chimeric channel proteins (hCa(v)3.1/S3S4 and hCa(v)3.2/S3S4) were produced by exchanging fourteen amino acids in the hCa(v)3.1 domain IV S3-S4 linker region and the corresponding region of hCa(v)3.2 between each other. The ProTx-I sensitivity was markedly reduced in the hCa(v)3.1/S3S4 chimera as compared to the original hCa(v)3.1 channel, while the hCa(v)3.2/S3S4 chimera exhibited greater ProTx-I sensitivity than the original hCa(v)3.2 channel. These results suggest that the domain IV S3-S4 linker in the hCa(v)3.1 channel may contain residues involved in the interaction of ProTx-I with T-type Ca(2+) channels.
Ohkubo
Tsuyako
T
Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Japan. ookut1@college.fdcnet.ac.jp
Yamazaki
Jun
J
Kitamura
Kenji
K
D000595:Amino Acid Sequence; D000818:Animals; D020747:Calcium Channels, T-Type / Q000737:chemistry / Q000187:drug effects*; D006801:Humans; D015640:Ion Channel Gating; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D013111:Spider Venoms / Q000737:chemistry* / Q000494:pharmacology; D014982:Xenopus laevis
C121855:CACNA1G protein, human; C479952:CACNA1H protein, human; D020747:Calcium Channels, T-Type; C470625:ProTx-I peptide; D013111:Spider Venoms