MRPL44
Mitochondrial Ribosomal Protein L44
Gene Information Card
| Symbol | MRPL44 |
|---|---|
| Full Name | Mitochondrial Ribosomal Protein L44 |
| Gene Type | Protein coding |
| Chromosomal Location | 2q36.1 |
| NCBI Gene ID | 65080 ncbi.nlm.nih.gov/gene/65080 |
| Ensembl ID | ENSG00000115977 |
| UniProt ID | Q9H9J2 |
| OMIM ID | 611849 |
| HGNC ID | 16652 |
| Aliases | MRP-L44, COXPD16, L44mt |
Description
MRPL44 encodes a 39S subunit protein of the mitochondrial ribosome, essential for mitochondrial translation. The protein is a component of the large ribosomal subunit and is required for the assembly and stability of the mitochondrial ribosome. Mutations in MRPL44 cause combined oxidative phosphorylation deficiency type 16 (COXPD16), characterized by hypertrophic cardiomyopathy and lactic acidosis.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Combined oxidative phosphorylation deficiency 16 (COXPD16) | Loss-of-function mutations impair mitochondrial ribosome assembly, reducing translation of mtDNA-encoded oxidative phosphorylation subunits, leading to energy deficiency. | ClinVar, OMIM #611849 |
| Hypertrophic cardiomyopathy (secondary) | MRPL44 deficiency disrupts mitochondrial protein synthesis in cardiac muscle, causing energy failure and compensatory hypertrophy. | OMIM, PubMed |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Heart | 12.5 | Medium |
| Skeletal muscle | 10.8 | Medium |
| Liver | 8.2 | Low |
| Kidney | 7.6 | Low |
| Brain | 6.1 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HeLa | 14.3 | Moderate expression |
| HEK293 | 13.1 | Moderate expression |
| K562 | 9.8 | Low expression |
| HepG2 | 8.5 | Low expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.467C>T (p.Ala156Val) | Missense | Unknown | Reduces MRPL44 stability and mitochondrial ribosome assembly; associated with COXPD16 |
| c.542G>A (p.Arg181Gln) | Missense | Unknown | Impairs large subunit formation; reported in COXPD16 patients |
Mutation functional classification
Loss of Function (LOF)
Missense mutations (e.g., p.Ala156Val, p.Arg181Gln) reduce protein stability and disrupt mitochondrial ribosome assembly, leading to decreased mitochondrial translation.
Gain of Function (GOF)
No gain-of-function mutations reported.
Dominant Negative (DN)
No dominant-negative mutations reported; inheritance is autosomal recessive.
View complete mutation data：
Gene Ontology (GO)
| • mitochondrial large ribosomal subunit | • structural constituent of ribosome |
| • mitochondrial translation | • ribosome assembly |
Pathways
• Mitochondrial translation
• Oxidative phosphorylation
Protein Summary
MRPL44 is a 37.5 kDa protein (332 amino acids) localized to the mitochondrial matrix. It is a component of the 39S large subunit of the mitochondrial ribosome, where it interacts with other ribosomal proteins and rRNA to facilitate translation of 13 mtDNA-encoded oxidative phosphorylation subunits. The protein contains a conserved ribosomal protein L44 domain. Defects in MRPL44 cause combined oxidative phosphorylation deficiency 16 (COXPD16).
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