Summary: Voltage gated calcium channel IQ domain
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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 . The interaction regulates two self-regulatory calcium dependent feedback mechanism, calcium dependent inactivation (CDI), and calcium-dependent facilitation (CDF).
Van Petegem F, Chatelain FC, Minor DL Jr; , Nat Struct Mol Biol. 2005;12:1108-1115.: Insights into voltage-gated calcium channel regulation from the structure of the CaV1.2 IQ domain-Ca2+/calmodulin complex. PUBMED:16299511 EPMC:16299511
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This tab holds annotation information from the InterPro database.
InterPro entry IPR014873
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 4 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).
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Curation and family details
|Number in seed:||25|
|Number in full:||724|
|Average length of the domain:||34.30 aa|
|Average identity of full alignment:||52 %|
|Average coverage of the sequence by the domain:||1.83 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||6|
|Download:||download the raw HMM for this family|
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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the Ca_chan_IQ domain has been found. There are 16 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.
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