Table 1. Features of 2Y5Y and 4OAA (inward affinity inactivator-bound and outward occluded states of LacY, respectively).

The shift in the numbering between the location in the diagram (Figure 1) and the actual residue number in the protein is due to missing residues between the structures.

Name	Residues in sequence	Location in structure
N-terminal cross 1	Leu 70-Leu 72	Border between TMSs 2–3
N-terminal cross 2	Tyr 113-Gly 115	Mid-TMS4
Edge of N-terminal quadrant	Leu 178-Lys 188	C-terminal half of TMS6
Edge of C-terminal quadrant	Ala 207-Ser 209	Middle of interdomain linker; end of small helical segment protruding from TMS7*
Big blue cross (C-terminal quadrant)	Phe 341-Phe 356	N-terminal half of TMS11
Big red cross (C-terminal quadrant)	Ala 361-Ile 376	C-terminal half of TMS11

^*) There are two additional helical units which are close together when the inward face of the transporter is closed.