C CARRIER 2 The carrier is open X enters from outside and to the outside binds at a binding site Carriers are conduits that are ated by two 8 "doors that are never open at the same time. Binding site The outer gate closes and X becomes occluded, still attached to its binding site 6 The outer gate closes, occluding an empty cycle can also flow in reverse order 4 X exits and enters th The inner gate opens nside of the cell with X still bound