Fig 5.

Structure of Methanocaldococcus jannaschii S2P. (Left) The top view of S2P (PDB accession number 3B4R) shows the presumed lateral gate formed by transmembrane helix 1 (TM1) on one side and TM5 and TM6 on the other side. S2P with an opened lateral gate is shown in blue, and S2P with a closed lateral gate is shown in green. The catalytic Zn²⁺ ion is depicted as a red ball. (Based on reference 40.) (Right) Side views of the molecular surface of S2P in the open and closed states. To illustrate the relative distance, TM1 and TM6 are shown in red. The rest of the molecule is shown in purple.