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-1G gives rise to T-type calcium currents. T-type calcium channels belong to the 'low-voltage activated (LVA)' group and are strongly blocked by mibefradil. A particularity of this type of channel is an opening at quite negative potentials and a voltage-dependent inactivation. T-type channels serve pacemaking functions in both central neurons and cardiac nodal cells and support calcium signaling in secretory cells and vascular smooth muscle. They may also be involved in the modulation of firing patterns of neurons which is important for information processing as well as in cell growth processes. Highly expressed in brain, in particular in the amygdala, subthalamic nuclei, cerebellum and thalamus. Moderate expression in heart; low expression in placenta, kidney and lung. Also expressed in colon and bone marrow and in tumoral cells to a lesser extent. Highly expressed in fetal brain, but also in peripheral fetal tissues as heart, kidney and lung, suggesting a developmentally regulated expression. Isoform 4, isoform 7, isoform 18, isoform 19, isoform 24, isoform 25 and isoform 31 are adult-specific. Isoform 8, isoform 14, isoform 15, isoform 16, isoform 17, isoform 20, isoform 21, isoform 22, isoform 23, isoform 26, isoform 27, isoform 28, isoform 29 and isoform 30 are fetal-specific. Isoform 1, isoform 2, isoform 6, isoform 9, isoform 11, isoform 12 and isoform 13 are expressed in both fetus and adult. 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. The linker region between repeat III and IV probably plays a role in the inactivation of the channel. The C-terminal part may be implicated in the anchoring of the protein to the membrane by interfering with or restricting its lateral diffusion. In response to raising of intracellular calcium, the T-type channels are activated by CaM-kinase II. 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. Belongs to the calcium channel alpha-1 subunit (TC 1.A.1.11) family. CACNA1G subfamily.