Functions as a voltage-gated inward-rectifying Ca(2+) channel (VDCC) across the plasma membrane that mediates sucrose-induced Ca(2+) influx in autotrophically grown leaf cells. Acts as the major ROS-responsive Ca(2+) channel and is the possible target of Al-dependent inhibition. Plays a regulatory role in defense responses. Inhibited by Al(3+). Homodimer. By high salinity, PEG, cold shock, and abscisic acid (ABA). 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). Belongs to the calcium channel alpha-1 subunit (TC 1.A.1.11) family. Two pore calcium channel subfamily.