In Gram-negative microorganisms, be that as it may, Shine Dalgarno succession presence isn't mandatory for the ribosome to find an initiator codon, since the cancellation of Against Shine Dalgarno arrangement from 16S rRNA doesn't prompt interpretation commencement at non-legitimate locales. Also, various prokaryotic mRNAs don't have Shine Dalgarno arrangements by any means. What essentially draws in the ribosome to mRNA commencement area is ribosomal protein S1, which ties to AU-rich groupings found in numerous prokaryotic mRNAs 15-30 nucleotides upstream of start-codon. It ought to be noticed, that S1 is just present in Gram-negative microorganisms, being missing from Gram-positive species.