UPF3B

This gene encodes a protein that is part of a post-splicing multiprotein complex involved in both mRNA nuclear export and mRNA surveillance. The encoded protein is one of two functional homologs to yeast Upf3p. mRNA surveillance detects exported mRNAs with truncated open reading frames and initiates nonsense-mediated mRNA decay (NMD). When translation ends upstream from the last exon-exon junction, this triggers NMD to degrade mRNAs containing premature stop codons. This protein binds to the mRNA and remains bound after nuclear export, acting as a nucleocytoplasmic shuttling protein. It forms with Y14 a complex that binds specifically 20 nt upstream of exon-exon junctions. This gene is located on the long arm of chromosome X. Two splice variants encoding different isoforms have been found for this gene.

Full Name

UPF3B, Regulator Of Nonsense Mediated MRNA Decay

Function

Involved in nonsense-mediated decay (NMD) of mRNAs containing premature stop codons by associating with the nuclear exon junction complex (EJC) and serving as link between the EJC core and NMD machinery. Recruits UPF2 at the cytoplasmic side of the nuclear envelope and the subsequent formation of an UPF1-UPF2-UPF3 surveillance complex (including UPF1 bound to release factors at the stalled ribosome) is believed to activate NMD. In cooperation with UPF2 stimulates both ATPase and RNA helicase activities of UPF1. Binds spliced mRNA upstream of exon-exon junctions. In vitro, stimulates translation; the function is independent of association with UPF2 and components of the EJC core.

Biological Process

Biological Process brain development Source:Ensembl
Biological Process mRNA transport Source:UniProtKB-KW
Biological Process neuron projection development Source:Ensembl
Biological Process nuclear-transcribed mRNA catabolic process, nonsense-mediated decay Source:UniProtKB1 Publication
Biological Process positive regulation of neuron differentiation Source:Ensembl
Biological Process positive regulation of translation Source:UniProtKB1 Publication

Cellular Location

Nucleus
Cytoplasm
Shuttling between the nucleus and the cytoplasm.

Involvement in disease

Intellectual developmental disorder, X-linked, syndromic 14 (MRXS14):
A disorder characterized by significantly below average general intellectual functioning associated with impairments in adaptive behavior and manifested during the developmental period. MRXS14 patients manifest intellectual disability associated with other variable signs such as autistic features, slender build, poor musculature, long, thin face, high-arched palate, high nasal bridge, and pectus deformities.