Likewise the distance between (+, Loop B ′ )SER174 and (-, Loop E ′′ )SER145 is shorter for bound or "more compressed" pockets, compared to unbound or "more enlarged" pockets, as shown in Figure ii. This distance distribution suggests that the movement of Loop B ′ , determined by the presence or absence of a ligand in the pocket, may influence that of LYS189 on Loop F ′ to which it is covalently connected. To monitor this, the distributions of the distance between (+, Loop F ′ )LYS189 and (-, Loop E ′′ )SER145 are also shown in Figure . The two distances always show a positive correlation, which is stronger in unbound (less compressed) pockets (Figure iii), indicating that the movement of loop B ′ conducts effectively to Loop F ′ , especially when there are no constrained, but can be affected by the pulling action of glycine mediating the interaction between Loop B ′ and Loop E ′′ . In turn, LYS189, located on the Loop F ′ protrusion, forms part of the complementary side of the pocket between the first two subunits, and is positioned near Loop C on the principal side of that pocket, as seen in Figure ). When the corresponding pocket is occupied, Loop C, where ASN219 is located, acts as a lid to cap the ligand, while the protrusion of Loop F ′ , with LYS189, may act as a secondary complementary lid that reinforces Loop C capping.