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Cav2.2

calcium channel, voltage-dependent, N type, alpha 1B subunit
Synonyms: ca2.2 BIII CACNN Cav2.2 CACNL1A5 CACNA1B. Symbol: Cacna1b

Introductions


The N-type calcium channels, also known as a1B or Cav2.2, are high voltage activated (HCA) calcium channels found presynaptically. For a longer introduction, see page 502 in the review [477]. See also the Channelpedia entry for Cav2.1, as this subunit is similar in many respects.

Genes


GeneID: 257648 Cacna1b calcium channel, voltage-dependent, N type, alpha 1B subunit [ Rattus norvegicus ]

Cacna1b : calcium channel, voltage-dependent, N type, alpha 1B subunit

RGD ID Chromosome Position Species
628852 3 2842948-3039747 Rat
735793 2 24461895-24618672 Mouse
1347795 9 140772241-141019076 Human

Transcripts


Acc No Sequence Length Source
NM_001195199 NCBI
NM_147141 NCBI
NM_007579 NCBI
NM_001042528 NCBI
NM_000718 NCBI

Ontologies


Accession Name Definition Evidence
GO:0043198 dendritic shaft Cylindric portion of the dendrite, directly stemming from the perikaryon, and carrying the dendritic spines. IDA
GO:0005886 plasma membrane The membrane surrounding a cell that separates the cell from its external environment. It consists of a phospholipid bilayer and associated proteins. IDA
GO:0043025 neuronal cell body The portion of a neuron that includes the nucleus, but excludes all cell projections such as axons and dendrites. IDA
GO:0043679 axon terminus Terminal inflated portion of the axon, containing the specialized apparatus necessary to release neurotransmitters. The axon terminus is considered to be the whole region of thickening and the terminal button is a specialized region of it. IDA
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: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:0019717 synaptosome Any of the discrete particles (nerve-ending particles) formed from the clublike presynaptic nerve endings that resist disruption and are snapped or torn off their attachments when brain tissue is homogenized in media isosmotic to plasma. IDA
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

Interactions


G proteins

See figure 10 in [94] for the mechanism of G protein modulation in calcium channels and the effect of palmitoylation on the interaction of Cav-beta subunits with the I–II linker.

Neurokinin 1 Receptor

Unlike R-type channels encoded by CaV2.3, L-type (CaV1.3), N- type (CaV2.2), and P/Q-type (CaV2.1) channels are inhibited, but not stimulated, through Neurokinin 1 receptors. [89]

Beta 3 Subunit

Overexpressed beta 3 subunit (12.5 ng/cell cRNA) significantly suppressed N- and R-type, but not L-type calcium channel currents at holding potentials of 60 and 80 mV.[92]

Roscovitine

Roscovitine, a potent inhibitor of cyclin-dependent kinases 1, 2, and 5, slows the deactivation of P/Q (Cav2.1) and N-type (Cav2.2) calcium channels. [93]

Proteins


Structures


The Cav2.2 subunit consists of four homologous domains (I–IV), each consisting of six trans- membrane (TM) segments. The domains are linked by intracellular loops and have intracellular N and C termini. (see Fig. 1A) in [88]

See also figure 7 in [90] for a structural connection between Cav2.1 and Cav2.2.

Distributions


presynaptic

Expressions


Cav2.2 can be found in retinal ganglion cells. [259]

Functionals


Cav2.2 control the excitability in retinal ganglion cells and thus are crucial for the development of the visual system. [250]

Kinetics


Models


The most detailed model can be found in [250]. It is from hippocampal mossy fiber boutons.

For a Hodgkin Huxley rate equation for the Ca2.2 (= N-type) current, see [260].

[1] CaN (Model ID = 6)

AnimalCat 43
CellType RGC
Age 34 Days
Temperature36.0°C
Reversal 135.0 mV
Ion Ca +
Ligand ion
Reference S J Huang et. al; Neuroscience 1998 Jul
mpower 2.0
mAlpha (0.1*(v-20)/(1-exp(-(v-20)/10))) If v neq 20
mBeta 0.4*exp(-(v+25)/18)
hpower 1.0
hAlpha 0.01*exp(-(v+50)/10)
hBeta 0.1/(1+exp(-(v+17)/17))

MOD xml channelML

References


[88 : 19903821]
[89 : 17050807]
[90 : 18958281]
[92 : 15024042]
[93 : 15951378]
[94 : 16049174]
[95 : 16267232]
[96 : 11606638]
[250 : 18057200]
[259 : 9607715]
[260 : 11371174]
[477 : 11031246]
[478 : 15000525]
[555 : 8107970]

Credits


Editor : Admin.

Contributors : Rajnish Ranjan, Michael Schartner

To cite : [Editor], [Contributors]. Accessed on [Date] Channelpedia , http://channelpedia.epfl.ch/ionchannels/79