Voltage-gated, high-affinity calcium channel involved in calcium influx in response to some environmental stresses as well as exposure to mating pheromones. Functions together with MID1 to ensure that adequate levels of Ca(2+) are supplied to PMR1 to sustain secretion and growth. Required for growth in low-calcium environments. Interacts with MID1 to form a Ca(2+) influx channel. Belongs to the calcium channel alpha-1 subunit (TC 1.A.1.11) family.