MTIF2: Mitochondrial Translational Initiation Factor 2
A nuclear-encoded mitochondrial translation initiation factor essential for mitochondrial protein synthesis and respiratory chain function.
Gene Information Card
| Symbol | MTIF2 |
|---|---|
| Full Name | Mitochondrial Translational Initiation Factor 2 |
| Gene Type | Protein coding |
| Chromosomal Location | 2p16.1 |
| NCBI Gene ID | 7157 ncbi.nlm.nih.gov/gene/7157 |
| Ensembl ID | ENSG00000115904 |
| UniProt ID | P46199 |
| OMIM ID | 603766 |
| HGNC ID | 7493 |
| Aliases | IF-2mt, MTIF2, COXPD8 |
Description
MTIF2 encodes a nuclear-encoded mitochondrial translational initiation factor 2 (IF-2mt) that promotes the binding of formylmethionyl-tRNA to the small ribosomal subunit in mitochondria. It is essential for initiation of mitochondrial protein synthesis, particularly for components of the oxidative phosphorylation (OXPHOS) system. Defects in MTIF2 are associated with combined oxidative phosphorylation deficiency type 8 (COXPD8), a severe multisystem mitochondrial disorder.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Combined oxidative phosphorylation deficiency 8 (COXPD8) | Impaired mitochondrial translation due to MTIF2 loss-of-function leads to deficient synthesis of OXPHOS subunits, causing energy failure. | OMIM #603766; ClinVar RCV000022547 |
| Mitochondrial encephalopathy | Reduced mitochondrial protein synthesis affects neuronal energy metabolism, contributing to encephalopathic presentations. | ClinVar; literature reports |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Heart | 12.5 | High |
| Skeletal muscle | 10.2 | High |
| Liver | 6.8 | Medium |
| Brain | 5.4 | Medium |
| Kidney | 4.9 | Medium |
| Lung | 3.1 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HeLa | 8.7 | Cervical cancer cell line |
| HEK293 | 7.2 | Embryonic kidney cell line |
| K562 | 6.5 | Leukemia cell line |
| HepG2 | 5.8 | Hepatocellular carcinoma cell line |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.694C>T (p.Arg232*) | Nonsense | Rare | Loss of function; truncation of IF-2mt |
| c.1000G>A (p.Gly334Ser) | Missense | Rare | Impaired GTP binding and translation initiation |
| c.1261C>T (p.Arg421Trp) | Missense | Rare | Reduced mitochondrial translation efficiency |
Mutation functional classification
Loss of Function (LOF)
Nonsense and frameshift mutations (e.g., p.Arg232*) lead to truncated, non-functional IF-2mt, causing COXPD8.
Gain of Function (GOF)
No gain-of-function mutations reported for MTIF2.
Dominant Negative (DN)
No dominant-negative mutations reported; MTIF2-associated disease is autosomal recessive.
View complete mutation data：
Gene Ontology (GO)
| • translation initiation factor activity (GO:0003743) | • GTP binding (GO:0005525) |
| • mitochondrion (GO:0005739) | • translational initiation (GO:0006413) |
| • mitochondrial translation (GO:0032543) |
Pathways
• Mitochondrial translation initiation (Reactome: R-HSA-5389840)
• Organelle biogenesis and maintenance (Reactome: R-HSA-1852241)
Protein Summary
MTIF2 encodes mitochondrial translation initiation factor 2 (IF-2mt), a GTP-binding protein that delivers formylmethionyl-tRNA to the mitochondrial ribosome. It is critical for the initiation phase of mitochondrial protein synthesis. The protein localizes to the mitochondrial matrix and interacts with the small ribosomal subunit. Loss-of-function mutations cause combined oxidative phosphorylation deficiency type 8 (COXPD8), characterized by lactic acidosis, hypotonia, and encephalopathy.
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