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Amino Acid Sequence of the Calcium Activated Potassium Channel (BK) In the Skate, Leucoraja Erinacea
Author(s) -
King Benjamin,
Clusin William T.,
Kao Peter
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.695.10
Subject(s) - skate , gating , calcium activated potassium channel , ion channel , extracellular , microbiology and biotechnology , homology (biology) , homology modeling , potassium channel , chemistry , biology , biophysics , amino acid , biochemistry , receptor , enzyme , fishery
Ca‐activated K channels were first described in the electroreceptor of the skate which has excitable receptor cells. Ca activated B K channels are also present in auditory hair cells, and their AA sequence and structure are known. While most Ca activated K channels respond to both Cai and voltage, the currents in skate electroreceptor are voltage insensitive. Assemblies of transcriptome and draft whole genome sequences from skate embryos were analyzed to find the ortholog of human gene, KCNMA1, that encodes the principal subunit. Ca‐activated K channels consist of 7 membrane spanning regions (S0–S6) and 4 intracellular domains (S7 – S10). Comparison of the 1147 AA skate channel with the mouse B K channel shows high homology, especially in S0 – S10, and in the pore region. There is complete homology of S0 – S3, S5, S6, the pore and S10. The voltage sensor region of S4 and also S7 show one amino acid change. S9 shows 3 changes, and S8 4 changes. The largest variations are in the S8 – S9 linker (which is missing a region of 155 AA's) and in the extracellular region preceding S0, which has only about 50% homology, and also contains a region of 33 AA's not present in mouse or human. Since the extracellular portion of S0 is known to tether the voltage gate, this could explain the apparent lack of voltage gating. The expression and splicing of B K channels in the electroreceptor is under investigation.