Table 1.
Homologue COX subunits and COX assembly factors in the yeast Saccharomyces cerevisiae and human.
| YEAST | HUMAN | ROLE | ||
|---|---|---|---|---|
| GENE | PROTEIN | GENE | PROTEIN | |
| Catalytic core (mtDNA encoded structural subunits) | ||||
| COX1 | Cox1 | MTCOXI | COX1 | Catalytic core subunits |
| COX2 | Cox2 | MTCOXII | COX2 | |
| COX3 | Cox3 | MTCOXIII | COX3 | |
| Core protective shield (nDNA encoded structural subunits) | ||||
| COX4 | Cox4 | COXVb | COX5b | Subunits required for COX assembly and function |
| COX5a | Cox5a | COXIV-1 | COX4-1 | |
| COX6 | Cox6 | COXVa | COX5a | |
| COX7 | Cox7 | COXVIIa | COX7a | |
| COX8 | Cox8 | COXVIIc | COX7c | |
| COX9 | Cox7a | COXVIc | COX6c | |
| - | - | COXVIIb | COX7b | |
| -- | -- | COXVIII | COX8 | |
| COX12 | Cox9 | COXVIb | COX6b | Non-essential subunits |
| COX13 | Cox10 | COXVIa | COX6a | |
| Expression of catalytic core subunits | ||||
| MSS116 | Mss116 | - | - | Helicase involved in splicing of all COX1 and COB introns |
| Component of the RNA degradosome | ||||
| SUV3 | Suv3 | - | - | Helicase involved in COX1 aI5β intron splicing |
| Stability of intron-containing COX1 and COB transcripts Component of the RNA degradosome |
||||
| MRS1 | Mrs1 | - | - | Required for COX1 aI5β intron splicing Required for excision of the COB bI3 intron |
| MNE1 | Mne1 | - | - | Required for COX1 aI5β intron splicing |
| MSS18 | Mss18 | - | - | Required for COX1 aI5β intron splicing |
| Additional unidentified function | ||||
| COX24 | Cox24 | - | - | Required for splicing of aI2 and aI3 COX1 introns |
| Required for COX1 mRNA translation | ||||
| NAM2 | Nam2 | - | - | Required for COX1 aI4 intron splicing |
| CCM1 | Ccm1 | - | - | Required for COX1 aI4 intron splicing |
| PET309 | Pet309 | Yeast: Translational activator of COX1 mRNA | ||
| LRPPRC | LRPPRC | Human: mitochondrial mRNA stability | ||
| MSS51 | Mss51 | - | - | Translational activator of COX1 mRNA |
| Cox1 chaperone required for its stability/ maturation/assembly |
||||
| YGR021w | Ygr021w | Yeast: No role on COX biogenesis | ||
| TACO1 | TACO1 | Human: COX1 mRNA translational activator | ||
| PET111 | Pet111 | - | - | Translational activator of COX2 mRNA |
| PET54 | Pet54 | - | - | Translational activator of COX3 mRNA |
| Required for COX1 aI5β intron splicing and translation | ||||
| PET122 | Pet122 | - | - | Translational activator of COX3 mRNA |
| PET494 | Pet494 | - | - | Translational activator of COX3 mRNA |
| Membrane insertion and processing of catalytic core subunits | ||||
| OXA1 | Oxa1 | OXA1 | OXA1 | Membrane insertion of COX subunits, cytochrome b and ATPase proteolipid |
| COX20 | Cox20 | COX20 | COX20 | Cox2 chaperone. Presentation of Cox2-precursor to the IMP complex |
| COX18 | Cox18 | COX18 | COX18 | Export of the Cox2 C-terminus tail |
| MSS2 | Mss2 | -- | -- | Export of the Cox2 C-terminus tail |
| PNT1 | Pnt1 | -- | -- | Export of the Cox2 C-terminus tail |
| IMP1 | Imp1 | -- | -- | Responsible for the maturation of precursor Cox2 |
| IMP2 | Imp2 | IMMP2L | IMMP2L | Required for the stability and activity of Imp1 |
| SOM1 | Som1 | -- | -- | Third component of the yeast IMP complex. It could play a role in substrate recognition |
| Copper Metabolism and Insertion into catalytic core subunits | ||||
| COX17 | Cox17 | COX17 | COX17 | Delivery of copper to Sco1 and Cox11 |
| SCO1 | Sco1 | SCO1 | SCO1 | Transfer of copper to COX and/or reduction of cysteine |
| SCO2 | SCO2 | residues in subunit 2 | ||
| COX11 | Cox11 | COX11 | COX11 | Stable formation of the CuB and Mg centers |
| COX19 | Cox19 | COX19 | COX19 | CX9C proteins. They could play roles in redox control and copper trafficking in the intermembrane space |
| COX23 | Cox23 | COX23 | COX23 | |
| PET191 | Pet191 | PET191 | PET191 | |
| CMC1 | Cmc1 | CMC1 | CMC1 | |
| CMC2 | Cmc1 | CMC2 | CMC2 | |
| Heme A Biosynthesis | ||||
| COX10 | Cox10 | COX10 | COX10 | Farnesylation of protoheme |
| COX15 | Cox15 | COX15 | COX15 | Conversion of heme o to heme a |
| YAH1 | Yah1 | FDX2 | FDX2 | Collaborates with Cox15 in heme o hydroxylation |
| ARH1 | Arh1 | ADR | ADR | Collaborates with Cox15 in heme o hydroxylation |
| Assembly / Unknown | ||||
| COX16 | Cox16 | COX16 | COX16 | Unknown function |
| PET117 | Pet117 | - | -- | Unknown function |
| PET100 | Pet100 | -- | -- | Formation of assembly intermediates containing Cox7, Cox8, and Cox9 |
| SHY1 | Shy1 | SURF1 | SURF1 | Catalyzes an assembly step involving Cox1 |
| COX14 | Cox14 | - | - | Binds Cox1 and is required for its stability/maturation/assembly |
| COA1 | Coa1 | -- | -- | Binds Cox1 and is required for its stability/maturation/assembly |
| COA2 | Coa2 | -- | -- | Required for Cox1 stability/maturation/assembly |
|
COA3/ COX25 |
Coa3 Cox25 |
-- | -- | Binds Cox1 and is required for its stability/maturation/assembly |
|
CMC3/ COA4 |
Cmc3 Coa4 |
-- | -- | CX9C protein involved in late stages of COX assembly |