. Author manuscript; available in PMC: 2017 Feb 18.

Published in final edited form as: Nature. 2016 Aug 18;536(7616):354–358. doi: 10.1038/nature19095

ED Table 3. Subunit-subunit interactions for the supernumerary subunits.

	Primary core subunit	Subunit interactions	Notes
42 kDa	ND2	ND2, ND4, 49 kDa (N-terminus), ESSS, KFYI, B14.5b, B13	Nucleoside kinase fold; does not contact hydrophilic core subunits or B14+SDAP-α

39 kDa	PSST	ND1, ND3 (class 2 only), ND6, 75 kDa, 30 kDa, PSST, TYKY, 18 kDa, 13 kDa, B14	Short-chain dehydrogenase/reductase fold²⁰ with bound NAD(P)(H)²¹
18 kDa	75 kDa	75 kDa, 51 kDa, 49 kDa, 30 kDa, TYKY, 39 kDa, 10 kDa, B17.2, B14	Four-strand β-sheet with helix located between 75 and 30 kDa

15 kDa	ND2	ND2, ND3, ND4L, ND6, PGIV, SGDH, B16.6, B14.5b	CHCH domain; IMS¹³

13 kDa	TYKY	75 kDa, 49 kDa, TYKY, 39 kDa, B17.2	Zinc-binding domain²² at the interface of TYKY, 75 and 49 kDa
10 kDa	24 kDa	75 kDa, 51 kDa, 24 kDa, 18 kDa	Present in the three-subunit flavoprotein subcomplex with 51 and 24 kDa
AGGG	ND5	ND5, B12	1 TMH; uncertain assignment of AGGG and B12 between chains j and k
ASHI	ND5	ND4, ND5, B22, B15	1 TMH; large globular domain on the matrix face, TMH crosses transverse helix
ESSS	ND4	ND4, ND5, 42 kDa, PDSW, SGDH, B22, B15, B14.5b	1 TMH; poorly resolved N-terminus on matrix face; possible disulphide 112 to PDSW 154.
KFYI	ND2	42 kDa, B14.5b	1 TMH; attached to complex by B14.5b
MNLL	ND4	ND4, PDSW, SGDH	1 TMH
MWFE	ND1	ND1, ND6, TYKY, PGIV, B17.2, B16.6, B14.5a	1 TMH; runs alongside ND1 TMH1 at proposed entrance to Q-binding site
PGIV	ND1	ND1, ND2, ND4, 15 kDa, MWFE, SGDH, B16.6, B14.5b, B9	Two CHCH domains; IMS¹³
PDSW	ND4	ND4, ND5, ESSS, MNLL, SGDH, B18, B17, B15, B14.5b	Extensive helix structure on IMS face; two likely internal disulphides (112-124, 76-83); possible disulphide 154 to ESSS-112
SDAP-α	30 kDa	B14	ACP on the hydrophilic domain¹⁶
SDAP-β	ND5	ND5, ASHI, B22, B17, B12	ACP on the membrane domain¹⁶
SGDH	ND4	ND2, ND4, ND5, ND6, 15 kDa, ESSS, MNLL, PDSW, PGIV, B22, B17, B16.6, B14.5b	1 TMH; long helix running along the IMS face of the membrane domain
B22	ND5	ND4, ND5, ASHI, SDAP-β, SGDH, B17, B15, B12	LYR protein that binds SDAP-β
B18	ND5	ND5, AGGG, PDSW, B17	CHCH domain; IMS¹³
B17.2	TYKY	ND1, 75 kDa, PSST, TYKY, 18 kDa, 13 kDa, MWFE, B14.5a	Three-strand β-sheet and long loop running across hydrophilic domain
B17	ND5	ND5, PDSW, SDAP-β, SGDH, B22	1 TMH; helix on the matrix face, β-strand in IMS augments β-hairpin between ND5 TMHs
B16.6	ND1	ND1, ND3, ND6, 49 kDa, TYKY, 15 kDa, MWFE, PGIV, SGDH, B14.5a, B9	1 TMH; 6S-residue helix that crosses the membrane then turns along the IMS face
B15	ND4	ND4, ND5, ASHI, PDSW, B22, B14.7	1 TMH; long helix runs across the matrix face of the membrane domain
B14.7	ND2	ND2, ND4, ND5, SGDH, B15	4 TMHs; on the anchor of the transverse helix; likely disulphide 18-75
B14.5a	49 kDa	75 kDa, 51 kDa, 49 kDa, 30 kDa, TYKY, MWFE, B17.2, B16.6, B13	Long loop structure over hydrophilic domain
B14.5b	ND2	ND2, ND4, 42 kDa, 15 kDa, ESSS, KFYI, PDSW, PGIV, SGDH, B15	2 TMHs; anchors KFYI to complex
B14	30 kDa	75 kDa, 49 kDa, 30 kDa, PSST, 39 kDa, 18 kDa, SDAP-α,	LYR protein that binds SDAP-α¹⁵
B13	30 kDa	49 kDa, 30 kDa, 42 kDa, B14.5a	Three-helix bundle
B12	ND5	ND5, SDAP-β, AGGG, B22	1 TMH; uncertain assignment of AGGG and B12 between chains j and k
B9	ND1	ND1, ND3, ND6, TYKY, 15 kDa, PGIV, B16.6	1 TMH
B8	75 kDa	75 kDa	Thioredoxin-like fold³⁸. Possible disulphide 23-57