TABLE 4. Knowledge about the supernumerary subunits of B. taurus complex I.

B. taurus subunit*	H. sapiens subunit*	Subcomplex†	Sequence information	Predicted TMHs‡
10 kDa	NDUFV3	Iα and Iλ		0
18 kDa	NDUFS4	Iα and Iλ		0
15 kDa	NDUFS5	Iα only	CX9C motif, intermembrane space37	0
13 kDa	NDUFS6	Iα and Iλ	PFAM zinc-finger motif CX8HX15CX2C	0
MWFE	NDUFA1	Iα only		1
B8	NDUFA2	Iα and Iλ		0
B9	NDUFA3	Iα only		1
B13	NDUFA5	Iα and Iλ		0
B14	NDUFA6	Iα only	LYR motif32	0
B14.5a	NDUFA7	Iα and Iλ		0
PGIV	NDUFA8	Iα only	Two CX9C motifs, PFAM CHCH domain intermembrane space37	0
39 kDa	NDUFA9	Iα only	Short-chain dehydrogenase reductase family, NADP binding26,27	0
42 kDa	NDUFA10	Iα only (low level)	Similarity to deoxynucleoside kinases24	0
B14.7	NDUFA11	Iα (Iλ at low level)		3 or 4
B17.2	NDUFA12	Iα and Iλ		0
B16.6	NDUFA13	Iα and Iλ		1
SDAP	NDUFAB1	both Iα Iβ	Acyl-carrier protein29,30	0
MNLL	NDUFB1	Iβ		0 (or 1)
AGGG	NDUFB2	Iβ		1 (or 0)
B12	NDUFB3	Iβ		1
B15	NDUFB4	both Iα and Iβ		1
SGDH	NDUFB5	Iβ		1
B17	NDUFB6	Iβ		1
B18	NDUFB7	Iβ	CX9C motif, intermembrane space37	0
ASHI	NDUFB8	Iβ		1
B22	NDUFB9	Iβ	LYR motif32	0
PDSW	NDUFB10	Iβ		0
ESSS	NDUFB11	Iβ		1
KFYI	NDUFC1	none		1
B14.5b	NDUFC2	Iβ (low level)		1 or 2

^*The former subunit MLRQ (NDUFA4) is no longer considered a subunit of complex I⁶⁰.

^†Subcomplex Iλ, which contains the seven hydrophilic core subunits and eight to nine supernumerary subunits, is considered to represent a significant portion of the hydrophilic domain of complex I. Subcomplex Iα, which contains all the subunits of subcomplex Iλ plus core subunit ND6 and nine to ten additional supernumerary subunits, represents the hydrophilic domain of complex I plus associated membrane subunits. Subcomplex Iβ, which contains ND4 and ND5 and 12 to 13 supernumerary subunits, represents part of the membrane domain³.

^‡TMHs were predicted using TMHMM2⁵², HMMTOP2⁵³ and the TOPCONS suite⁵⁴ (seven methods in total) and are presented as consensus values with less represented values in brackets and single outliers discarded.