A protein linked to the 5' termini of both RNA components of the cowpea mosaic virus genome.

Evidence is presented for the presence of a protein covalently bound to the 5' termini of both M and B RNA components of CPMV. The protein is found to be linked in both cases to the 5' phosphate of the dinucleotide pUpAp, derived by ribonuclease digestion of the RNA. The intact protein is not required for infectivity or for in vitro translation of the RNA in cell-free extracts.