1.A.87.1.2
Plant Ca²⁺ channel protein, Mid1 complementary activity 2, MCA2 (Iida et al. 2013).  Catalyzes mechanical stress-induced Ca²⁺ influx.  It is tetrameric with a small transmembrane domain and a large cytoplasmic domain (Shigematsu et al. 2014).  MCA1 and MCA2 both have their N-termini located extracellularly and their C-termini located intracellularly. An EF hand-like motif, coiled-coil motif, and Plac8 motif may all be in the cytoplasm, suggesting that the activities of both channels can be regulated by intracellular Ca²⁺ and protein interactions (Kamano et al. 2015). However hydropathy plots suggest that the Plac8 domain may be transmembrane with 3 TMSs.  mca1 but not mca2 mutants show defects in root entry into hard agar, whereas mca2 but not mca1 mutants are defective in Ca²⁺ uptake in A. thaliana roots (Hamilton et al. 2015).