Logged in as a Visitor.
calcium channel, voltage-dependent, L type, alpha 1F subunit
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 ), 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).
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 ).
Cacna1f : calcium channel, voltage-dependent, L type, alpha 1F subunit
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 )
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 ), 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 ). Auxiliary beta and alpha2-delta subunits modulate channel kinetics and targeting of the alpha1 subunit to the membrane (Neely et al., 1993 ; Tareilus et al., 1997 ; Yasuda et al., 2004 ).
The Cav1.4 VGCC is expressed in the retina and localizes at ribbon synapses in cone and rod photoreceptors (Morgans et al., 2005 ), as well as in the inner nuclear and ganglion cell layer (McRory et al., 2004 ). The channel is also detectable in plasma and mast cells, although its role in the immune system is not fully understood. (Peloquin )
Cav1.4 channels may be ideally suited to support tonic release of glutamate at the ribbon synapse under constantly depolarized conditions. (Peloquin )
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 ; McRory et al., 2004 ; Doering et al., 2007 ) at room temperature in 15 or 20 mM Ba2+.