RNA Cap-Binding Complex (CBC)

The RNA Cap-Binding Complex (CBC) is a heterodimeric protein complex composed of Nuclear Cap-Binding Protein Subunit 1 (NCBP1/CBP80) and Nuclear Cap-Binding Protein Subunit 2 (NCBP2/CBP20). It plays a pivotal role in the mRNA biogenesis pathway by specifically recognizing and binding the 7-methylguanosine (m7G) cap at the 5' end of nascent RNA polymerase II transcripts (UniProt Q09161, P52298). This binding event is essential for coordinating early mRNA processing steps, including pre-mRNA splicing, 3' end polyadenylation, and the subsequent export of mature mRNA from the nucleus to the cytoplasm (PubMed: 32855415). In the cytoplasm, the CBC is typically replaced by eIF4E to initiate steady-state translation, although it remains involved in the pioneer round of translation and nonsense-mediated decay (PubMed: 21241880). Dysregulation of the CBC, particularly the overexpression of NCBP1, has been implicated in the progression of various malignancies, including lung and breast cancers, where it facilitates the expression of oncogenic factors (PubMed: 33414415). Additionally, many viruses, such as Influenza A and HIV-1, exploit the CBC to ensure the efficient processing and export of viral mRNAs (PubMed: 26861437). Therapeutic strategies targeting the CBC aim to disrupt its cap-binding affinity or the NCBP1-NCBP2 interaction, thereby inhibiting the production of proteins essential for viral replication or tumor growth. While specific small-molecule inhibitors are largely in the experimental stage, drugs like Ribavirin have been shown to interfere with cap-dependent processes (PubChem CID 37542).

Other names

Nuclear Cap-Binding Protein ComplexNCBP1-NCBP2 ComplexCBP80-CBP20 ComplexNCBP Complex

Inhibition of the interaction between the 5' m7G cap and the CBC subunits, or disruption of the NCBP1-NCBP2 heterodimer, to prevent mRNA maturation and export.