Fig. 2.

R218, M222, Y419, and Y423 contribute to the cytoplasmic gate. (A) Homology model of rVMAT2 based on the structure of YajR (PDB ID code 3WDO) in a lumen-facing conformation. TM5 and TM11 are shown as opaque. R218 and M222 from TM5, and Y419 and Y423 from TM11, are represented as sticks. The close-up view indicates the predicted interactions between these residues as part of the cytoplasmic gate. (B) [³H]Reserpine binding by whole cells expressing different replacements at positions 218, 222, and 419, as described in Fig. 1. (C and D) [³H]Serotonin transport (C) and [³H]TBZ binding (D) to digitonin-permeabilized cells. Results presented are averages of at least two repeats, each point in duplicate; error bars indicate SE.