Evolutionary genomics reveals the premetazoan origin of opposite gating polarity in animal-type voltage-gated ion channels.
Electrical signaling in animals ensures the rapid and accurate transmission of information, often carried by voltage-gated Na(+), Ca(2+) and K(+) channels that are activated by membrane depolarization. In heart and neurons, a distinct type of ion channel called the hyperpolarization-activated, cyclic nucleotide-regulated (HCN) channel is activated by membrane hyperpolarization. Recent genomic studies have revealed that animal-type voltage-gated Na(+) channels (Liebeskind BJ, et al. 2011. Proc Natl Acad Sci U S A. 108:9154) had evolved in choanoflagellates, one of the unicellular relatives of animals. To date, HCN channels have been considered to be animal-specific. Here, we demonstrate the presence of an HCN channel homolog (SroHCN) in the choanoflagellate protist Salpingoeca rosetta. SroHCN contains highly conserved functional domains and sequence motifs that are correlated with the unique biophysical activities of HCN channels. These findings provide novel genomic insights into the evolution of complex electrical signaling before the emergence of multicellular animals.
Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA. xinjiang.cai@med.nyu.edu
Xinjiang
X
Cai
D000595:Amino Acid Sequence; D000818:Animals; D001703:Biophysics; D015220:Calcium Channels / Q000235:genetics*; D056897:Choanoflagellata / Q000235:genetics*; D054815:Cyclic Nucleotide-Gated Cation Channels / Q000235:genetics; D019143:Evolution, Molecular; D023281:Genomics / Q000379:methods; D008969:Molecular Sequence Data; D009712:Nucleotides, Cyclic / Q000235:genetics; D010802:Phylogeny; D024642:Potassium Channels, Voltage-Gated / Q000235:genetics*; D017434:Protein Structure, Tertiary / Q000235:genetics; D016415:Sequence Alignment; D015222:Sodium Channels / Q000235:genetics*
D015220:Calcium Channels; D054815:Cyclic Nucleotide-Gated Cation Channels; D009712:Nucleotides, Cyclic; D024642:Potassium Channels, Voltage-Gated; D015222:Sodium Channels