NEMF
Developmental stage
Expressed in the developing brain.
Function
Key component of the ribosome quality control complex (RQC), a ribosome-associated complex that mediates the extraction of incompletely synthesized nascent chains from stalled ribosomes as well as their ubiquitin-mediated proteasomal degradation (PubMed:25578875, PubMed:32726578, PubMed:33406423, PubMed:33909987). Thereby, frees 60S subunit ribosomes from the stalled translation complex and prevents the accumulation of nascent polypeptide chains that are potentially toxic for the cell (PubMed:25578875, PubMed:33406423, PubMed:33909987). Within the RQC complex, NEMF specifically binds stalled 60S ribosomal subunits by recognizing an exposed, nascent chain-conjugated tRNA moiety and promotes the recruitment of LTN1 to stalled 60S subunits (PubMed:25578875). Following binding to stalled 60S ribosomal subunits, NEMF mediates CAT tailing by recruiting alanine-charged tRNA to the A-site and directing the elongation of stalled nascent chains independently of mRNA or 40S subunits, leading to non-templated C-terminal alanine extensions (CAT tails) (PubMed:33406423, PubMed:33909987). Mainly recruits alanine-charged tRNAs, but can also other amino acid-charged tRNAs (PubMed:33406423, PubMed:33909987). CAT tailing is required to promote ubiquitination of stalled nascent chains by different E3 ubiquitin-protein ligases (PubMed:33909987). In the canonical RQC pathway (RQC-L), CAT tailing facilitates LTN1-dependent ubiquitination by exposing lysine residues that would otherwise remain buried in the ribosomal exit tunnel (By similarity). In the alternative RQC pathway (RQC-C) CAT tailing creates an C-degron mainly composed of alanine that is recognized by the CRL2(KLHDC10) and RCHY1/PIRH2 E3 ligases, leading to ubiquitination and degradation of stalled nascent chains (PubMed:33909987). NEMF may also indirectly play a role in nuclear export (PubMed:16103875).
Involvement in disease
Intellectual developmental disorder with speech delay and axonal peripheral neuropathy
IDDSAPN
An autosomal recessive disorder characterized by mild global developmental delay, mild to moderate intellectual disability, motor impairment, unsteady or ataxic gait, and severe speech delay apparent in the first years of life. Signs of a peripheral axonal neuropathy, including progressive distal muscle weakness and atrophy of the lower limbs, foot and hand deformities, and dysarthria, are observed in most patients. Some patients may have autistic features or attention deficit-hyperactivity disorder.
None
The disease is caused by variants affecting the gene represented in this entry.
Sequence Similarities
Belongs to the NEMF family.
Tissue Specificity
Expressed in brain, heart, liver, lung, spleen, and skeletal muscle. Also expressed at lower levels in stomach and testis.
Cellular localization
- Cytoplasm
- Cytosol
- Nucleus
Alternative names
SDCCAG1, NEMF, Ribosome quality control complex subunit NEMF, Antigen NY-CO-1, Nuclear export mediator factor, Serologically defined colon cancer antigen 1