Table 4.

Yeast complex IV subunits and their human homologs. The table also shows Complex IV assembly factors that are associated with diseases.

	Yeast Gene	Genome	pet Mutant	Human Gene	Function
Enzyme Subunits	COX1	mitochondrial	N/A	MTCO1	catalysis
	COX2	mitochondrial	N/A	MTCO2	catalysis
	COX3	mitochondrial	N/A	MTCO3	structure/catalysis
	COX5a	nuclear	yes	COX4	structure
	COX5b 1	nuclear	no	-	structure
	COX6	nuclear	yes	COX5A	structure
	COX4	nuclear	yes	COX5B	structure
	COX13	nuclear	no	COX6A	structure
	COX12	nuclear	yes	COX6B	structure
	COX9	nuclear	yes	COX6C	structure
	COX7	nuclear	yes	COX7A	structure
	-	nuclear	-	COX7B	structure
	COX8	nuclear	no	COX7C	structure
	-	nuclear	-	COX8	structure
	-	nuclear	-	NDUFA4/COXFA4	structure
Assembly Factors	COX20	nuclear	yes	COX20/FAM36A	membrane insertion of Cox2
	COX14	nuclear	yes	COX14	regulation of COX1 expression, maintenance of monomeric Cox1
	PET117	nuclear	yes	PET117	couples synthesis of heme a to COX assembly
	PET191	nuclear	yes	COA5	required for COX assembly
	PET100	nuclear	yes	PET100	required for COX assembly
	COA6	nuclear	no	COA6	maturation of the CuA site
	COX25/COA3	nuclear	yes	COA3	translational regulation of COX1 mRNA
	COX15	nuclear	yes	COX15	conversion of heme o to heme a
	COX10	nuclear	yes	COX10	farnesylation of heme b
	SCO1	nuclear	yes	SCO1	maturation of the CuA site
	SCO2	nuclear	no	SCO2	maturation of the CuA site
	SHY1	nuclear	yes	SURF1	hemylation of Cox1

¹ Yeast subunit 5b is a paralog of subunit 5a and under standard conditions of growth is present at low concentrations [134].