Channelpedia

cacng8

Description: calcium channel, voltage-dependent, gamma subunit 8
Gene: Cacng8     Synonyms: cacng8

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Introduction

The protein encoded by CACNG8 (also known as FLJ16240; FLJ30598) is a type I transmembrane AMPA receptor regulatory protein (TARP). TARPs regulate both trafficking and channel gating of the AMPA receptors. This gene is part of a functionally diverse eight-member protein subfamily of the PMP-22/EMP/MP20 family and is located in a cluster with two family members, a type II TARP and a calcium channel gamma subunit. The mRNA for this gene is believed to initiate translation from a non-AUG (CUG) start codon.

http://www.ncbi.nlm.nih.gov/gene/59283


Experimental data


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Gene

Phylogenetic analysis suggests that all c subunits evolved from a single ancestral gene through tandem repeat and chromosome duplication (Burgesse [1312], Chu [1311]). Based on sequence homology and chromosomal linkage the c subunits can be divided into three clusters: (c1, c6), (c5, c7), and (c2, c3, c4, c8) (Burgesse [1312], Chu [1311]). See also the phylogenetic tree, fig.2 in Black [478].

The four c subunits identified as regulators of AMPA receptor function (c2, c3, c4, and c8; the TARPs) are widely expressed in the brain and share highly conserved sequences that are quite distinct from c1 and c6 (Arikkath [1324], Black [478]).

RGD ID Chromosome Position Species
628808 1 64068324-64088556 Rat
732323 7 3394459-3415366 Mouse
732322 19 54466294-54486139 Human

Cacng8 : calcium channel, voltage-dependent, gamma subunit 8


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Transcript

Acc No Sequence Length Source
NM_080696 n/A n/A NCBI
NM_133190 n/A n/A NCBI
NM_031895 n/A n/A NCBI

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Ontology

Accession Name Definition Evidence
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
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

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Interaction

The most distinct features of the TARPs are the terminal PDZ-binding motifs overlapped with PKA phosphorylation sites. The terminal TTPV motif is known to interact with PSD-95 in the postsynaptic density and the binding is regulated by the PKA motif immediately preceding the PDZ-binding motif (Chetkovich [1325], Choi [1326]). In addition to the critical PDZ-binding motif, the C-terminal regions of the four c subunits known as the TARPs (c2, c3, c4, c8) also contain regulatory sites that control AMPA receptor targeting. (Chen [1310])


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Protein


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Structure

The eight calcium channel c subunits share a predicted structure that includes four transmembrane domains with intracellular N- and C- termini (Fig. 1 in Chen [1310]). They are members of a large protein superfamily (pfam00822, a subset of the tetraspanin supergroup) that also includes claudins, proteins that are important components of tight junctions in epithelia. The c subunits share with the claudins a conserved GLW motif of unknown significance in the first extracellular loop. Chen [1310]

The cytoplasmic C-terminal regions of the TARPs (to which cacng8 = gamma8 = c8 belongs) contain a number of regulatory sites including a PDZ-binding motif. This PDZ-binding motif (TTPV) is critical for targeting AMPA receptors to the synapse. Chen [1310]


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Distribution


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Expression

The four c subunits identified as regulators of AMPA receptor function (c2, c3, c4, and c8; the TARPs) are widely expressed in the brain and share highly conserved sequences that are quite distinct from c1 and c6 (Arikkath [1324], Black [478]).


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Functional


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Kinetics


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Model


References

Chen RS et al. Calcium channel gamma subunits: a functionally diverse protein family.
Cell Biochem. Biophys., 2007 , 47 (178-86).

Arikkath J et al. Auxiliary subunits: essential components of the voltage-gated calcium channel complex.
Curr. Opin. Neurobiol., 2003 Jun , 13 (298-307).

1322

Arikkath J et al. Gamma 1 subunit interactions within the skeletal muscle L-type voltage-gated calcium channels.
J. Biol. Chem., 2003 Jan 10 , 278 (1212-9).

478

Black JL The voltage-gated calcium channel gamma subunits: a review of the literature.
J. Bioenerg. Biomembr., 2003 Dec , 35 (649-60).

Choi J et al. Phosphorylation of stargazin by protein kinase A regulates its interaction with PSD-95.
J. Biol. Chem., 2002 Apr 5 , 277 (12359-63).


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Credits

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