The alpha-2/delta subunit of voltage-dependent calcium channels regulates calcium current density and activation/inactivation kinetics of the calcium channel. Acts as a regulatory subunit for P/Q-type calcium channel (CACNA1A), N-type (CACNA1B), L-type (CACNA1C OR CACNA1D) and possibly T-type (CACNA1G). Overexpression induces apoptosis.
Modulatory effects of auxiliary alpha(2)delta(2) and gamma(5) subunits on intramembrane charge movement originating from the expressed Ca(v)3.1 calcium channel were investigated. Inward current was blocked by 1mM La(3+). Voltage dependences of Q(on) and Q(off), kinetics of ON- and OFF-charge movement, and I(max)/Q(max) ratio were measured in the absence and the presence of an auxiliary subunit. The alpha(2)delta(2) subunit accelerated significantly both ON- and OFF-charge movement. I(max)/Q(max) ratio and Q(on)-V, Q(off)-V relations were not affected. Coexpression of the alpha(2)delta(2) subunit may accelerate channel transitions between individual closed states, but not the transition from the last closed channel state into an open state. Coexpression of the gamma(5) subunit accelerated the decay of the ON-charge transient and enhanced I(max)/Q(max) ratio. These effects suggest improvement of the coupling between the charge movement and the channel opening due to facilitation of transitions between individual closed states and the transition between the last closed state and an open state.
The CACNA2D2 gene, a new subunit of the Ca(2+)-channel complex, was identified in the homozygous deletion region of chromosome 3p21.3 in human lung and breast cancers. Expression deficiency of the CACNA2D2 in cancer cells suggests a possible link of it to Ca(2+) signaling in the pathogenesis of lung cancer and other cancers. We investigated the effects of overexpression of CACNA2D2 on intracellular Ca(2+) contents, mitochondria homeostasis, cell proliferation, and apoptosis by adenoviral vector-mediated wild-type CACNA2D2 gene transfer in 3p21.3-deficient nonsmall cell lung cancer cell lines. Exogenous expression of CACNA2D2 significantly inhibited tumor cell growth compared with the controls. Overexpression of CACNA2D2 induced apoptosis in H1299 (12.5%), H358 (13.7%), H460 (22.3%), and A549 (50.1%) cell lines. Levels of intracellular free Ca(2+) were elevated in AdCACNA2D2-transduced cells compared with the controls. Mitochondria membrane depolarization was observed prior to apoptosis in Ad-CACNA2D2 and Adp53-transduced H460 and A549 cells. Release of cyt c into the cytosol, caspase 3 activation, and PARP cleavage were also detected in these cells. Together, these results suggest that one of the pathways in CACNA2D2-induced apoptosis is mediated through disruption of mitochondria membrane integrity, the release of cyt c, and the activation of caspases, a process that is associated with regulation of cytosolic free Ca(2+) contents.
Catalysis of the transmembrane transfer of a calcium ion by a voltage-gated channel. A voltage-gated channel is a channel whose open state is dependent on the voltage across the membrane in which it is embedded.
A process that is carried out at the cellular level which results in the assembly, arrangement of constituent parts, or disassembly of a neuromuscular junction.
Protein involved in the transport of calcium ions. Calcium is essential for a variety of bodily functions, such as neurotransmission, muscle contraction and proper heart function.
Protein involved in the transport of ions. Such proteins are usually transmembrane and mediate a movement of ions across cell membranes. Transport may be passive (facilitated diffusion; down the electrochemical gradient), or active (against the electrochemical gradient). Active transport requires energy which may come from light, oxidation reactions, ATP hydrolysis, or cotransport of other ions or molecules.
Protein involved in the transport of a molecule (metabolite, protein, etc), a ion or an electron across cell membranes, inside the cell or in a tissue fluid.
Cell membrane glycoprotein forming a channel in a biological membrane selectively permeable to calcium ions. Calcium is essential for a variety of bodily functions, such as neurotransmission, muscle contraction and proper heart function.
Protein which is part of a transmembrane protein complex that forms a hydrophilic channel across the lipid bilayer through which specific inorganic ions can diffuse down their electrochemical gradients. The channels are usually gated and only open in response to a specific stimulus, such as a change in membrane potential (voltage-gated) or the binding of a ligand (ligand-gated channel).
Protein which is a component of a voltage-gated channel. Voltage-gated ion channels are responsible for the electrical activity in a variety of cell types. They probably exist in all life forms.
A reference proteome is a set of protein sequences derived from a complete proteome which constitutes a defined standard for a particular user community. Reference proteomes are manually defined according to a number of criteria. They cover the proteomes of well- studied model organisms and other proteomes of interest for biomedical and biotechnological research. Reference proteomes have been selected to provide broad coverage of the tree of life, and constitute a representative cross-section of the taxonomic diversity to be found within UniProtKB.
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