Premium
Novel Ca V 2.1 clone replicates many properties of Purkinje cell Ca V 2.1 current
Author(s) -
Richards Kathryn S.,
Swensen Andrew M.,
Lipscombe Diane,
Bommert Kurt
Publication year - 2007
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.1460-9568.2007.05912.x
Subject(s) - gene isoform , protein subunit , alternative splicing , purkinje cell , biology , voltage dependent calcium channel , microbiology and biotechnology , complementary dna , biophysics , calcium , chemistry , biochemistry , cerebellum , neuroscience , gene , organic chemistry
The P‐type calcium current is mediated by a voltage‐sensing Ca V 2.1 α subunit in combination with modulatory auxiliary subunits. In Purkinje neurones, this current has distinctively slow inactivation kinetics that may depend on alternative splicing of the α subunit and/or association with different Ca V β subunits. To better understand the molecular components of P‐type calcium current, we cloned a Ca V 2.1 cDNA from total mouse brain. The full‐length Ca V 2.1 isoform that we isolated (GenBank AY714490 ) contains sequences recently shown to be present in Purkinje neurones. In agreement with previously published work, the alternatively spliced amino acid V 421 , implicated in slow inactivation, was not encoded in AY714490 and was absent from reverse transcription‐polymerase chain reaction products generated from single Purkinje cells. Next, we studied the expression of the four known mouse auxiliary Ca V β 2 isoforms in Purkinje neurones. Confirmation of the presence of Ca V β 2a in Purkinje cells, previously shown by others to slow Ca V 2.1 kinetics, led us to characterize its influence on current dynamics. We studied currents generated by the clone AY714490 coexpressed in tsA201 cells with four different Ca V β subunits . In addition to the well‐documented slowing of open‐state inactivation kinetics, coexpression with the Ca V β 2a subunit also protected Ca V 2.1 channels from closed‐state inactivation and prevented the channel from inactivating during physiological trains of action potential‐like stimuli. This strong resistance to inactivation parallels the property of Purkinje neurone P‐type currents and is suggestive of a role for Ca V β 2a in modulating the inactivation properties of P‐type calcium currents in Purkinje neurones.