Table 1.

Structurally characterized ABC transporter systems, classified by TMD fold. The nomenclature of the fold classification is from³³. Note that while the outward facing conformation generally corresponds to the ATP (or suitable analogue) bound state, exceptions are evident in the structures of ADP bound to Sav1866 and nucleotide free BtuCD.

transporter	organism	nucleotide state	inward/outward	PDB ID	resolution	reference
Type I ABC importer fold
ModABC	A. fulgidus	apo	inward	2ONK	3.1 Å	22
MalFGK	E. coli	ATP	outward	2R6G	2.8 Å	23
ModAB	M. acetivorans	apo	inward	3D31	3.0 Å	25
MetNI	E. coli	apo	inward	3DHW	3.7 Å	26
Type II ABC importer fold
BtuCD	E. coli	apo or (VO2)4	outward	1L7V	3.2 Å	17
HI1470/1	H. influenzae	apo	inward	2NQ2	2.4 Å	20
BtuCDF	E. coli	apo	occluded	2QI9	2.6 Å	21
ABC exporter fold
Sav1866	S. aureus	ADP	outward	2HYD	3.0 Å	18
		AMPPNP	outward	2ONJ	3.4 Å	19
MsbA	S. typhimurium	AMPPNP	outward	3B60	3.7 Å	24
		ADP- vanadate	outward	3B5Z	4.2 Å
	E. coli	apo	inward	3B5W	5.3 Å
	V. cholerae	apo	inward	3B5X	5.5 Å