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Inhibition of BK Ca channel activity by association with calcineurin in rat brain
Author(s) -
Loane David J.,
Hicks Gareth A.,
Perrino Brian A.,
Marrion Neil V.
Publication year - 2006
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.2006.04931.x
Subject(s) - calcineurin , phosphatase , chemistry , bk channel , protein subunit , calmodulin , biophysics , r type calcium channel , calcium channel , biochemistry , microbiology and biotechnology , calcium , enzyme , biology , membrane potential , medicine , t type calcium channel , transplantation , organic chemistry , gene
Large conductance calcium‐activated potassium (BK Ca ) channels are regulated by a number of different protein kinases and phosphatases. The close association of enzymes and channel have been shown to underlie many examples of modulation. However, only the association of protein kinase A with the BK Ca channel has been detailed [Tian et al . (2003) J. Biol. Chem. , 278, 8669–8677]. We have found using reciprocal immunoprecipitations that the BK Ca channel associates with the calcium/calmodulin‐dependent phosphatase calcineurin, in Wistar rat brain. A HA‐tagged construct of the carboxyl terminus of rSlo 27 , a variant of the BK Ca channel that is abundant in the hippocampus [Ha et al . (2000) Eur. J. Biochem ., 267, 910–9218], was found to associate only with the B subunit of calcineurin. This data suggests that the majority of the interaction of the BK Ca channel with calcineurin is mediated by the B subunit of the phosphatase. This was confirmed by using glutathione‐ S ‐transferase (GST) fusion proteins of the linker regions between the S7–S10 hydrophobic domains in the carboxyl terminus of rSlo 27 , where only the B subunit of calcineurin interacted with regions between S7 and S9 of the channel. Addition of a constitutively active calcineurin (CaN 420 ) to inside‐out membrane patches excised from cultured hippocampal neurons resulted in a dramatic reduction in BK Ca channel open probability, with only very short‐duration events being apparent. These data suggest that BK Ca channel activity is inhibited by calcineurin, an effect mediated by the association of the calcineurin B subunit with the carboxyl terminus of the channel.