NCBP1
Description
The NCBP1 (nuclear cap binding protein subunit 1) is a protein-coding gene located on chromosome 9.
NCBP1, also known as 80 kDa nuclear cap-binding protein, is a subunit of the nuclear cap-binding complex (CBC). The CBC binds to the 5'-cap of pre-mRNAs and is involved in various processes, including pre-mRNA splicing, translation regulation, nonsense-mediated mRNA decay (NMD), RNA interference (RNAi) by microRNAs (miRNAs), and mRNA export. The CBC is essential for cell growth and viability.
NCBP1, also known as CBP80, is a crucial component of the nuclear cap-binding complex (CBC). The CBC binds to the 5' cap of pre-mRNAs during transcription and plays a role in various mRNA processing steps, including splicing, translation regulation, mRNA decay, and export. It facilitates mRNA export from the nucleus by interacting with the ALYREF/THOC4/ALY protein, recruiting the mRNA export machinery. The CBC is also involved in exporting U snRNA and intronless mRNAs. It's essential for the initial round of mRNA translation (pioneer round), before the CBC is replaced by the cytoplasmic cap-binding protein eIF4E. The pioneer round plays a critical role in nonsense-mediated mRNA decay (NMD), a process that eliminates aberrant mRNAs. The CBC enhances NMD by interacting with UPF1, promoting the interaction between UPF1 and UPF2. The CBC is also involved in a 'failsafe' NMD pathway, which is independent of the EJC complex. During cell proliferation, the CBC participates in microRNA (miRNA) biogenesis through its interaction with SRRT/ARS2, and is necessary for miRNA-mediated RNA interference. The CBC also acts as a negative regulator of PARN, inhibiting mRNA deadenylation. Within the CBC, NCBP1/CBP80 doesn't directly bind capped RNAs but stabilizes the movement of the N-terminal loop of NCBP2/CBP20, locking the CBC into a high-affinity cap-binding state. NCBP1/CBP80 associates with NCBP3 to form an alternative CBC, which is particularly important for mRNA export during cellular stress, such as viral infections. The conventional CBC with NCBP2 binds both snRNA and mRNA and participates in their export from the nucleus, whereas the alternative CBC with NCBP3 only binds mRNA, specifically playing a role in mRNA export. NCBP1/CBP80 is essential for cell growth and viability.
NCBP1 is also known as CBP80, NCBP, Sto1.
