TRANSLATION INITIATION FROM NON-AUG CODONS IN COS1 CELLS IS MESSENGER-RNA SPECIES-DEPENDENT

Sendai virus P/C mRNA, human erythrocyte membrane protein 4.1 mRNA and PDGF-B chain mRNA were used to test whether translation initiation fr om non-AUG codons in COS1 cells was mRNA species dependent. Site-direc ted mutants of the authentic translation start sites of these mRNAs to alternate start codons showed that while P/C mRNA is capable of initi ating translation from non-AUG start sites the other two mRNAs are not , Our study shows that translation initiation from non-AUG codons is m RNA species dependent and suggests that higher order structure of an m RNA determines the non-AUG translation start site. (C) 1994 Academic P ress, Inc.