Kinetic mechanism of Na⁺-coupled aspartate transport catalyzed by Glt_Tk.

ABSTRACT: It is well-established that the secondary active transporters Glt_Tk and Glt_Ph catalyze coupled uptake of aspartate and three sodium ions, but insight in the kinetic mechanism of transport is fragmentary. Here, we systematically measured aspartate uptake rates in proteoliposomes containing purified Glt_Tk, and derived the rate equation for a mechanism in which two sodium ions bind before and another after aspartate. Re-analysis of existing data on Glt_Ph using this equation allowed for determination of the turnover number (0.14 s^-1), without the need for error-prone protein quantification. To overcome the complication that purified transporters may adopt right-side-out or inside-out membrane orientations upon reconstitution, thereby confo

SUBMITTER: Trinco G 

PROVIDER: S-EPMC8211817 | biostudies-literature | 2021 Jun

REPOSITORIES: biostudies-literature