Channelpedia

Cav1.4

Description: calcium channel, voltage-dependent, L type, alpha 1F subunit
Gene: Cacna1f     Synonyms: cacna1f, cav1.4, ca1.4

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Introduction

Voltage-gated calcium channels (VGCCs), heteromultimeric protein complexes consisting of an alpha1 sub- unit, as well as ancillary beta, alpha2-delta, and possibly gamma subunits (Hofmann et al., 1994 [1220]), are a primary route through which calcium can enter cells.

CACNA1 (also known as JM8; OA2; AIED; COD3; COD4; JMC8; CORDX; CSNB2; CORDX3; CSNB2A; CSNBX2; Cav1.4 encodes Cav1.4, a member of the alpha-1 subunit family, L type, high voltage activated (HVA) calcium channel, found in the retina. It is also known as a1F. Calcium channels mediate the influx of calcium ions into the cell upon membrane polarization and consist of a complex of alpha-1, alpha-2/delta, beta, and gamma subunits in a 1:1:1:1 ratio. The alpha-1 subunit has 24 transmembrane segments and forms the pore through which ions pass into the cell. There are multiple isoforms of each of the proteins in the complex, either encoded by different genes or the result of alternative splicing of transcripts. Alternate transcriptional splice variants of the gene described here have been observed but have not been thoroughly characterized. Mutations in this gene have been shown to cause incomplete X-linked congential stationary night blindness type 2 (CSNB2).

http://www.ncbi.nlm.nih.gov/gene/778

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Gene

VGCCs are encoded by 10 genes, four of which encode the L-type calcium channel family and include Cav1.1, Cav1.2, Cav1.3 and Cav1.4 (Ertel et al., 2000 [1224]).

RGD ID Chromosome Position Species
621535 X 26908850-26937165 Rat
731993 X 7184229-7212322 Mouse
731992 X 49061523-49089833 Human

Cacna1f : calcium channel, voltage-dependent, L type, alpha 1F subunit

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Transcript

Acc No Sequence Length Source
NM_053701 n/A n/A NCBI
NM_019582 n/A n/A NCBI
NM_005183 n/A n/A NCBI
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Ontology

Accession Name Definition Evidence
GO:0043204 perikaryon The portion of the cell soma (cell body) that excludes the nucleus. IDA
GO:0016021 integral to membrane Penetrating at least one phospholipid bilayer of a membrane. May also refer to the state of being buried in the bilayer with no exposure outside the bilayer. When used to describe a protein, indicates that all or part of the peptide sequence is embedded in the membrane. IEA
GO:0005891 voltage-gated calcium channel complex A protein complex that forms a transmembrane channel through which calcium ions may pass in response to changes in membrane potential. IEA
GO:0016020 membrane Double layer of lipid molecules that encloses all cells, and, in eukaryotes, many organelles; may be a single or double lipid bilayer; also includes associated proteins. IEA
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Interaction

Temperature dependence of Cav1.4: With 20 mM Ba2+ as charge carrier, increasing the temperature from 23 °C to 37 °C increases whole-cell conductance, shifts the voltage-dependence of activation to more hyperpolarized voltages, and accelerates the degree of recovery from inactivation over a given time, but does not significantly alter the half-inactivation potential (Vh). (Peloquin [232])

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Protein

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Structure

Voltage-gated calcium channels (VGCCs), heteromultimeric protein complexes consisting of an alpha1 sub- unit, as well as ancillary beta, alpha2-delta, and possibly gamma subunits (Hofmann et al., 1994 [1220]), are a primary route through which calcium can enter cells. The alpha1 subunit forms the ion conducting pore and contains the ion selectivity filter and voltage sensors which gate the channel in response to changes in membrane potential (Hofmann et al., 1994 [1220]). Auxiliary beta and alpha2-delta subunits modulate channel kinetics and targeting of the alpha1 subunit to the membrane (Neely et al., 1993 [1221]; Tareilus et al., 1997 [1222]; Yasuda et al., 2004 [1223]).

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Distribution

See expression.

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Expression

The Cav1.4 VGCC is expressed in the retina and localizes at ribbon synapses in cone and rod photoreceptors (Morgans et al., 2005 [1225]), as well as in the inner nuclear and ganglion cell layer (McRory et al., 2004 [233]). The channel is also detectable in plasma and mast cells, although its role in the immune system is not fully understood. (Peloquin [232])

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Functional

Cav1.4 channels may be ideally suited to support tonic release of glutamate at the ribbon synapse under constantly depolarized conditions. (Peloquin [232])

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Kinetics

Cav1.4 channels have fast activation kinetics, ultraslow inactivation kinetics that may be the result of late openings, and the presence of a large window current which ranges from -20 mV to +20 mV (Koschak et al., 2003 [1226]; McRory et al., 2004 [233]; Doering et al., 2007 [1219]) at room temperature in 15 or 20 mM Ba2+.

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Model

References

231

Hemara-Wahanui A et al. A CACNA1F mutation identified in an X-linked retinal disorder shifts the voltage dependence of Cav1.4 channel activation.
Proc. Natl. Acad. Sci. U.S.A., 2005 May 24 , 102 (7553-8).

232

Peloquin JB et al. Temperature dependence of Cav1.4 calcium channel gating.
Neuroscience, 2008 Feb 19 , 151 (1066-83).

1219

Doering CJ et al. Cav1.4 encodes a calcium channel with low open probability and unitary conductance.
Biophys. J., 2005 Nov , 89 (3042-8).

1220

Hofmann F et al. Molecular basis for Ca2+ channel diversity.
Annu. Rev. Neurosci., 1994 , 17 (399-418).

1224

Ertel EA et al. Nomenclature of voltage-gated calcium channels.
Neuron, 2000 Mar , 25 (533-5).

1225

Morgans CW Localization of the alpha(1F) calcium channel subunit in the rat retina.
Invest. Ophthalmol. Vis. Sci., 2001 Sep , 42 (2414-8).

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Credits

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