TIMM44: Translocase of Inner Mitochondrial Membrane 44
Mitochondrial protein import regulator and its role in cellular energy metabolism
Gene Information Card
| Symbol | TIMM44 |
|---|---|
| Full Name | Translocase of Inner Mitochondrial Membrane 44 |
| Gene Type | Protein coding |
| Chromosomal Location | 19p13.2 |
| NCBI Gene ID | 10469 ncbi.nlm.nih.gov/gene/10469 |
| Ensembl ID | ENSG00000104879 |
| UniProt ID | O43615 |
| OMIM ID | 605058 |
| HGNC ID | 17316 |
| Aliases | TIM44, MIMT44 |
Description
TIMM44 (Translocase of Inner Mitochondrial Membrane 44) encodes a peripheral membrane protein of the mitochondrial inner membrane. It is a component of the TIM23 translocase complex, which mediates the import of nuclear-encoded precursor proteins into the mitochondrial matrix. TIMM44 interacts with mitochondrial heat shock protein 70 (mtHsp70) to drive protein translocation across the inner membrane. This gene is essential for mitochondrial biogenesis and cellular energy production.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Mitochondrial complex I deficiency | Impaired mitochondrial protein import reduces complex I assembly and function | ClinVar: pathogenic variants reported |
| Combined oxidative phosphorylation deficiency | Defective TIMM44 disrupts import of multiple OXPHOS subunits | OMIM: 605058 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Heart | 12.5 | High |
| Skeletal muscle | 10.2 | High |
| Liver | 8.1 | Medium |
| Brain | 7.3 | Medium |
| Kidney | 6.9 | Medium |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HeLa | 11.0 | Cervical carcinoma |
| HepG2 | 9.5 | Hepatocellular carcinoma |
| K562 | 7.8 | Leukemia |
| A549 | 8.2 | Lung carcinoma |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.287G>A (p.Arg96Gln) | Missense | Rare | Reduced protein stability and import efficiency |
| c.511C>T (p.Arg171Trp) | Missense | Rare | Impaired interaction with mtHsp70 |
Mutation functional classification
Loss of Function (LOF)
Missense mutations reduce TIMM44 stability or disrupt binding to mtHsp70, impairing mitochondrial protein import.
Gain of Function (GOF)
No gain-of-function mutations reported.
Dominant Negative (DN)
No dominant-negative mutations reported.
View complete mutation data：
Gene Ontology (GO)
| • Mitochondrial inner membrane | • Protein transmembrane transporter activity |
| • Protein import into mitochondrial matrix | • ATP-dependent protein translocation |
| • Chaperone binding |
Pathways
• Mitochondrial protein import (TIM23 complex)
• Oxidative phosphorylation
Protein Summary
TIMM44 is a 44 kDa peripheral membrane protein located on the inner mitochondrial membrane. It serves as an essential adaptor within the TIM23 translocase complex, tethering mtHsp70 to the import channel. This interaction provides the driving force for protein translocation into the mitochondrial matrix. TIMM44 is highly expressed in tissues with high energy demand, such as heart and skeletal muscle. Mutations in TIMM44 are associated with mitochondrial disorders, particularly complex I deficiency and combined oxidative phosphorylation deficiency.
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