Elasmobranchs detect small potentials using excitable cells of the ampulla of Lorenzini which have @entity460 -activated @entity3529 channels, first described in 1974. A distinctive feature of the outward current in voltage clamped ampullae is its apparent insensitivity to voltage. The sequence of a BK channel a isoform expressed in the ampulla of the skate was characterized. A signal peptide is present at the beginning of the gene. When compared to @entity1 isoform 1 (the canonical sequence), the largest difference was absence of a 59 @entity3689 region from the S8-S9 intra-cellular linker that contains the strex regulatory domain. The ampulla isoform was also compared with the isoform predicted in late skate embryos where strex was also absent. The BK voltage sensors were conserved in both skate isoforms. Differences between the skate and @entity1 BK channel included alternative splicing. Alternative splicing occurs at seven previously defined sites that are characteristic for BK channels in general and hair cells in particular. Skate BK sequences were highly similar to the @entity16516 and several other vertebrate species. Based on alignment of known BK sequences with the skate genome and transcriptome, there are at least two isoforms of Kcnma1a expressed in the skate. One of the b subunits (b4), which is known to decrease voltage sensitivity, was also identified in the skate genome and transcriptome and in the ampulla. These studies advance our knowledge of BK channels and suggest further studies in the ampulla and other excitable tissues.

XXXX activated @entity3529 channels in the electroreceptor of the skate confirmed by cloning. Details of subunits and splicing.

@entity1 :: ('9606', 'Species') :: ['human'] @entity3529 :: ('D011188', 'Chemical') :: ['K(+)'] @entity460 :: ('MESH:D002118', 'Chemical') :: ['calcium'] @entity16516 :: ('7868', 'Species') :: ['Australian ghost shark'] @entity3689 :: ('D000596', 'Chemical') :: ['amino acid']
@entity460 :: (MESH:D002118,Chemical) :: ['Calcium']
