Ca_chan_IQ Voltage gated calcium channel IQ domain
SMART ACC:	SM001062
Description:	Voltage gated calcium channels control cellular calcium entry in response to changes in membrane potential. The isoleucine-glutamine (IQ) motif in the voltage gated calcium channel IQ domain interacts with hydrophobic pockets of Ca2+/calmodulin (PUBMED:16299511). The interaction regulates two self-regulatory calcium dependent feedback mechanism, calcium dependent inactivation (CDI), and calcium-dependent facilitation (CDF).
InterPro ACC:	IPR014873
InterPro abstract:	Ca2+ ions are unique in that they not only carry charge but they are also the most widely used of diffusible second messengers. Voltage-dependent Ca2+ channels (VDCC) are a family of molecules that allow cells to couple electrical activity to intracellular Ca2+ signalling. The opening and closing of these channels by depolarizing stimuli, such as action potentials, allows Ca2+ ions to enter neurons … expand Ca2+ ions are unique in that they not only carry charge but they are also the most widely used of diffusible second messengers. Voltage-dependent Ca2+ channels (VDCC) are a family of molecules that allow cells to couple electrical activity to intracellular Ca2+ signalling. The opening and closing of these channels by depolarizing stimuli, such as action potentials, allows Ca2+ ions to enter neurons down a steep electrochemical gradient, producing transient intracellular Ca2+ signals. Many of the processes that occur in neurons, including transmitter release, gene transcription and metabolism are controlled by Ca2+ influx occurring simultaneously at different cellular locales. The pore is formed by the alpha-1 subunit which incorporates the conduction pore, the voltage sensor and gating apparatus, and the known sites of channel regulation by second messengers, drugs, and toxins [ PUBMED:14657414 ]. The activity of this pore is modulated by four tightly-coupled subunits: an intracellular beta subunit; a transmembrane gamma subunit; and a disulphide-linked complex of alpha-2 and delta subunits, which are proteolytically cleaved from the same gene product. Properties of the protein including gating voltage-dependence, G protein modulation and kinase susceptibility can be influenced by these subunits. Voltage-gated calcium channels are classified as T, L, N, P, Q and R, and are distinguished by their sensitivity to pharmacological blocks, single-channel conductance kinetics, and voltage-dependence. On the basis of their voltage activation properties, the voltage-gated calcium classes can be further divided into two broad groups: the low (T-type) and high (L, N, P, Q and R-type) threshold-activated channels. The voltage-gated calcium channel alpha 1 subunit contains an IQ domain, named for its isoleucine-glutamine (IQ) motif, which interacts with hydrophobic pockets of Ca2+/calmodulin [ PUBMED:16299511 ]. The interaction regulates two self-regulatory calcium dependent feedback mechanisms, calcium dependent inactivation (CDI), and calcium-dependent facilitation (CDF). collapse
Family alignment:	View the Family alignment or the Alignment consensus sequence
There are 5 198 Ca_chan_IQ domains in 5 178 proteins in SMART's NRDB database.

Taxonomic distribution of proteins containing Ca_chan_IQ domains

The tree below includes only several representative species and genera. The complete taxonomic breakdown of all proteins containing Ca_chan_IQ domains can be accessed here. Click the counts or percentage values to display the corresponding proteins.

Predicted cellular role

Cellular role:	Signalling

Relevant references for this domain

Primary literature for the Ca_chan_IQ domain is listed below. Automatically-derived, secondary literature is also available.

KEGG pathways involving proteins which contain this domain

This information is based on the mapping of SMART genomic protein database to KEGG orthologous groups. Percentages are related to the number of proteins containing a Ca_chan_IQ domain which could be assigned to a KEGG orthologous group, and not all proteins containing Ca_chan_IQ domains. Please note that proteins can be included in multiple pathways, ie. the numbers below will not add to 100%.

KEGG pathways

KEGG orthologous groups

3D structures in PDB containing this domain

Links to other resources describing this domain

InterPro	IPR014873
Pfam	Ca_chan_IQ