May function as one of the major voltage-gated Ca(2+) channel (VDCC) across the plasma membrane. May be involved in the regulation of cytosolic Ca(2+) and in growth and development. Acts as the major ROS-responsive Ca(2+) channel and is the possible target of Al-dependent inhibition. Determines sensitivity to T.viride xylanase elicitor. Plays a regulatory role in elicitor-induced defense responses and hypersensitive cell death. Inhibited by the VDCC blocker verapamil in yeast cells. Channel activity may be down-regulated by cytosolic Ca(2+) in rice cells. Inhibited by Al(3+) (By similarity). Measured in yeast knockout mutant cch1. Homodimer. Expressed in shoot, mature leaf, cultured cells, and at lower level in roots. Each of the two 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 (By similarity). Rescues the Ca(2+) uptake activity in yeast mutant cch1. Plants overexpressing TPC1 display reduced growth rate and dwarf phenotype, and seedlings show greening of roots under light conditions. The highest overexpressor line shows most severe phenotype including a death symptom, possibily due to Ca(2+) accumulation to toxic level. Belongs to the calcium channel alpha-1 subunit (TC 1.A.1.11) family. Two pore calcium channel subfamily.