1.A.62.2.4
TRIC family homologue of 213 aas and 7 TMSs; it's high resolution 3-d structure is known (PDB# 5H36). TRIC channels are implicated in Ca²⁺ signaling and homeostasis. Kasuya et al. 2016 presented crystal structures of two prokaryotic TRIC channels in the closed state and conducted structure-based functional analyses of these channels. Each trimer subunit consists of seven TMSs with two inverted 3 TMS repeats (Silverio and Saier 2011). The electrophysiological, biochemical and biophysical analyses revealed that TRIC channels possess an ion-conducting pore within each subunit, and that trimer formation contributes to the stability of the protein. The symmetrically related TMS2 and TMS5 helices are kinked at conserved glycine clusters, and these kinks are important for channel activity. The kinks in TMS2 and TMS5 generate lateral fenestrations at each subunit interface that are occupied by lipid molecules (Kasuya et al. 2016).