GO:0005846:   nuclear cap binding complex
A conserved heterodimeric protein complex that binds to the 5" terminal cap structure m7G(5")ppp(5")N of nascent eukaryotic RNA polymerase II transcripts such as pre-mRNA and U snRNA. The consists of proteins known as CBP20 and CBP80, binds to cap structures in the nucleus, and is involved in pre-mRNA splicing, 3"-end formation, and RNA nuclear export.