Translation initiation site of the coat protein messenger ribonucleic acid of the cowpea strain of tobacco mosaic virus.

The 5'-terminus of the coat protein messenger RNA of the cowpea strain of tobacco mosaic virus contains a m7G(5')ppp(5')Gp... cap group. Removal of this cap group followed by introduction of a 5'-terminal [32P]phosphomonoester onto the decapped RNA and use of this 32P-labeled RNA in nucleotide sequence studies establishes that the 5'-terminal nucleotide sequence of this RNA is m7G(5')ppp(5')GUAUUUGAUGAUGGCAUACUCGAUUCCGACUCCCUAGCU.... The codons following the two consecutive AUG sequences match the N-terminal amino acids of the coat protein of the cowpea strain of tobacco mosaic virus. Translation initiation complexes between wheat germ 80S ribosomes and this messenger RNA protect regions adjacent to the two consecutive AUG sequences of this messenger RNA from attack by ribonucleases. Therefore, one or both of these AUG sequences serve as sites for the initiation of translation of the coat protein messenger RNA of the cowpea strain of tobacco mosaic virus.