Thylakoid localized bestrophin-like proteins are essential for the CO concentrating mechanism of .

The green alga possesses a CO concentrating mechanism (CCM) that helps in successful acclimation to low CO conditions. Current models of the CCM postulate that a series of ion transporters bring HCO from outside the cell to the thylakoid lumen, where the carbonic anhydrase 3 (CAH3) dehydrates accumulated HCO to CO, raising the CO concentration for Ribulose bisphosphate carboxylase/oxygenase (Rubisco). Previously, HCO transporters have been identified at both the plasma membrane and the chloroplast envelope, but the transporter thought to be on the thylakoid membrane has not been identified.