Voltage-sensitive calcium channels (VSCC) mediate the entry of calcium ions into excitable cells and are also involved in a variety of calcium-dependent processes, including muscle contraction, hormone or neurotransmitter release, gene expression, cell motility, cell division and cell death. The isoform alpha-1D gives rise to L-type calcium currents. Long-lasting (L-type) calcium channels belong to the 'high-voltage activated' (HVA) group. They are blocked by dihydropyridines (DHP), phenylalkylamines, and by benzothiazepines. Voltage-dependent calcium channels are multisubunit complexes, consisting of alpha-1, alpha-2, beta and delta subunits in a 1:1:1:1 ratio. The channel activity is directed by the pore-forming and voltage-sensitive alpha-1 subunit. In many cases, this subunit is sufficient to generate voltage-sensitive calcium channel activity. The auxiliary subunits beta and alpha-2/delta linked by a disulfide bridge regulate the channel activity. Channel activity is further modulated, depending on the presence of specific delta subunit isoforms. Interacts (via IQ domain) with CABP1 and CABP4 in a calcium independent manner (By similarity). Interacts with RIMBP2 (By similarity). Additional isoforms seem to exist. Expressed in pancreatic islets and in brain, where it has been seen in cerebral cortex, hippocampus, basal ganglia, habenula and thalamus. Expressed in the small cell lung carcinoma cell line SCC-9. No expression in skeletal muscle. Each of the four internal repeats contains five hydrophobic transmembrane segments (S1, S2, S3, S5, S6) and one positively charged transmembrane segment (S4). S4 segments probably represent the voltage-sensor and are characterized by a series of positively charged amino acids at every third position. A change from seven to eight ATG trinucleotide repeats, resulting in an additional N-terminal methionine, has been found in a patient with non-insulin-dependent diabetes mellitus (NIDDM). The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. Gain of function variations affecting the gene represented in this entry may be associated with susceptibility to autism spetrum disorders. Expressed at 5% to 15% of isoform Neuronal-type in brain tissues, increased current density. Belongs to the calcium channel alpha-1 subunit (TC 1.A.1.11) family. CACNA1D subfamily.