Cap binding protein in eukaryotes is
Cap-binding protein in eukaryotic cytosolic translation is eIF4E, 24 kDa subunit of eIF4F complex also containing scaffold eIF4G and helicase eIF4A. eIF4E specifically binds 7-methylguanosine cap structure at 5' end of mRNA via aromatic stacking interactions with tryptophan residues, recruiting mRNA to 43S pre-initiation complex for scanning. Activity controlled by binding proteins 4E-BPs that sequester eIF4E under nutrient deprivation, phosphorylation influencing affinity, and availability limiting translation of oncogenic growth factor mRNAs characterized by complex 5' UTRs requiring helicas
Ref: Watson Molecular Biology of the Gene, 7th ed., Chapter 15, eIF4E cap-binding protein recognizing m7G cap