background:
The majority of mitochondrial-directed proteins are encoded by the nuclear genome and are transported to the mitochondria via regulated processes involving the mitochondrial Tom and Tim proteins (1). The mitochondrial Tim protein family is comprised of a large group of evolutionarily conserved proteins that are found in most eukaryotes (1,2). Import of nuclear-encoded precursor proteins into and across the mitochondrial inner membrane is mediated by two distinct complexes, the Tim23 complex and the Tim22 complex, which differ in their substrate specificity (1). Defects in Tim proteins are implicated in several neuro-degenerative diseases, suggesting important roles for Tim proteins in development and health (3,4). Tim8A and Tim8B, which map to human chromosomes Xq22.1 and 11q23.1-q23.2, respectively, are conserved proteins of the mitochondrial intermembrane space, which are organized in hetero-oligomeric complex with Tim13 (5,6,7). Tim8A is highly expressed in fetal and adult brain (5). Tim8A is mutated in deafness dystonia syndrome, a novel type of disease that causes severe neurological defects, thought to be caused by a defective mitochondrial protein transport system (5,8).
Function:
TIMM8A is a mitochondrial intermembrane chaperone that participates in the import and insertion of some multi-pass transmembrane proteins, such as metabolite transporters, from the cytoplasm into the mitochondrial inner membrane. The TIMM8A gene is mutated in Deafness Dystonia Syndrome (MTS/DFN-1) suggesting that it is required for normal neurologic development.
Subunit:
Heterohexamer; composed of 3 copies of TIMM8A and 3 copies of TIMM13, named soluble 70 kDa complex. Associates with the TIM22 complex, whose core is composed of TIMM22.
Subcellular Location:
Mitochondrion inner membrane; Peripheral membrane protein; Intermembrane side.
Tissue Specificity:
Highly expressed in fetal and adult brain, followed by fetal lung, liver and kidney. Also expressed in heart, placenta, lung, liver, kidney, pancreas, skeletal muscle and heart.
DISEASE:
Defects in TIMM8A are the cause of Mohr-Tranebjaerg syndrome (MTS) [MIM:304700]; also known as dystonia-deafness syndrome (DDS) or X-linked progressive deafness type 1 (DFN-1). It is a recessive neurodegenerative syndrome characterized by postlingual progressive sensorineural deafness as the first presenting symptom in early childhood, followed by progressive dystonia, spasticity, dysphagia, mental deterioration, paranoia and cortical blindness.
Defects in TIMM8A are the cause of Jensen syndrome (JENSS) [MIM:311150]; also known as opticoacoustic nerve atrophy with dementia. This X-
Similarity:
Belongs to the small Tim family.
Database links:
UniProtKB/Swiss-Prot: O60220.1
Important Note:
This product as supplied is intended for research use only, not for use in human, therapeutic or diagnostic applications.
|
|
