| Primary Identifier | IPR008369 | Type | Family |
| Short Name | VDCC_g5su |
| description | 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 []. 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-dependent calcium channel gamma (VDCCG) subunit family consistsof at least 8 members, which share a number of common structural features[]. Each member is predicted to possess 4 transmembrane domains, with intracellular N- and C-termini. The first extracellular loop contains a highly conserved N-glycosylation site and a pair of conserved cysteine residues. The C-terminal 7 residues of VDCCG-2, -3, -4 and -8 are also conserved andcontain a consensus site for phosphorylation by cAMP and cGMP-dependentprotein kinases, and a target site for binding by PDZ domain proteins [].The VDCCG-5 subunit was identified by genomic database searching, pursuingsequences similar to VDCCG-1 and -2. Mouse, human and rat isoforms havebeen cloned. VDCCG-5 is expressed in a range of tissues, including brain,kidney and testis []. |
