2.B.67.  The Light-driven K⁺ Carrier (MC2) Family 

The light-driven motor molecule, MC2, forms a selective K⁺ transporter through a single molecular transmembrane mechanism, and the light-driven rotary motion significantly accelerates ion transport, which endows the irradiated motor molecule with cytotoxicity and cancer cell selectivity (Yang et al. 2022). It consists of a central rotor and stator as well as two distal K⁺ binding domains.  Mechanistic studies revealed that the rotary motion of MC2 promotes K⁺ efflux, generates reactive oxygen species and activates caspase-3-dependent apoptosis in cancer cells. A single molecule vertically inserts and spans the lipid membrane to form a stable and selective K⁺ channel. Then, the rotary motion of the motor provides actuation energy to accelerate ion transport in the channel and realize light-gated function. These unique features can play a role in regulating intracellular K⁺ concentrations, presenting a new drug discovery strategy for the treatment of cancer and other diseases (Yang et al. 2022).