Nuclear cap-binding protein subunit 3 (NCBP3)

Associates with NCBP1/CBP80 to form an alternative cap- binding complex (CBC) which plays an integral role in mRNA export. NCBP3 functions as adapter protein linking the capped RNAs (m7GpppG-capped RNA) to NCBP1/CBP80.

Unlike the conventional CBC with NCBP2 which contrasts both small nuclear RNA (snRNA) and messenger (mRNA) and is included in their export from the nucleus, the alternative CBC with NCBP3 doesn't bind snRNA and associates only with mRNA thereby playing a part in only mRNA export. The alternative CBC is very important in cellular stress situations like virus infections and the NCBP3 activity is critical to inhibit virus growth (PubMed:26382858).