A putative prokaryote voltage-gated Ca(2+) channel with only one 6TM motif per subunit.
Until now, voltage-gated Ca(2+) channel proteins have been found only in eukaryotes. Here we report that a gene recently discovered in the eubacterium Bacillus halodurans codes for a protein closely related to eukaryotic Ca(2+) channels, but that has only one 6-transmembrane-segement (6TM) motif, instead of four, in its pore-forming subunit. This is supported by the comparison of consensus sequences, which, along with the patterns of residue conservation, indicates a similar structure in the membrane to voltage-gated K(+) channels. From this we hypothesize that Ca(2+) channels originally evolved in bacteria, and that the specific eubacteria protein highlighted here is an ideal candidate for structure determination efforts.
Durell
S R
SR
Molecular Structure Section, Laboratory of Experimental and Computational Biology, National Cancer Institute, National Institutes of Health, 9000 Rockville Pike, Bethesda, Maryland, 20892, USA.
Guy
H R
HR
D000595:Amino Acid Sequence; D015220:Calcium Channels / Q000737:chemistry*; D015640:Ion Channel Gating; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid
D015220:Calcium Channels