Fig. 4: The conformational change of Asc-1 during transport cycle.
From: Cryo-EM structure of the human Asc-1 transporter complex
a, b Structure comparison of Asc-1 apo and Asc-1 in complex with D-Ser shows only a slight movement of TM1a with D-Ser bound. c, d Structure comparison shows that Asc-1 in complex with D-Ser or L-Ala adopts different conformations. TM1a and TM6b are notably different. In the occluded conformation TM1a and TM6b are stabilized by a salt bridge between Glu257 and Arg339. Asc-1 apo and Asc-1 in complex with D-Ser adopt an inward open conformation while Asc-1 in complex with L-Ala adopts an occluded conformation. e The efflux transport assay of Asc-1-4F2hc complex. Oocytes were injected with 15 ng cRNA of human 4F2hc plus 15 ng human wild-type asc-1. After incubation of 5 days oocytes were preloaded with of 10 μM [14C]glycine for one hour. Subsequently oocytes were washed and efflux induced by addition of 1 mM of the listed amino acids. Net efflux was determined in NMDG-ND96 buffer. Data are presented as mean values ± SD of three experiments each with n = 8 oocytes.
