The cap-binding complex (CBC) consisting of NCBP2 and its adaptor NCBP1 is believed to bind all capped RNA and to be necessary for its processing and intracellular localisation. Nuclear cap-binding protein subunit 3 (NCBP3), together with NCBP1, forms an alternative CBC in higher eukaryotes. NCBP3 binds mRNA, associates with components of the mRNA processing machinery and contributes to poly(A) RNA export [].