Regarding Wobble Base-Pairing

Hi,

Possible Base Pairs

5' Anticodon	3' Codon
G	U,C
C	G
A	U
U	A,G

Say we have the codon AUG. According to the table, thanks to wobbling, a 3' G in the codon can base pair with a 5' C or U in the anticodon. This means the anticodon sequence could be CAU or UAU.

Obviously AUG is a start codon and thus codes for methionine. Because of wobble base-pairing, UAU can bind the AUG codon. UAU anticodons can also bind AUA codons by normal paring rules. AUA codons code for isoleucine. This means both a methionine and isoleucine tRNA can recognize AUG codons. I understand the first methionine in translation is charged and an isoleucine tRNA won't interfere, but how does the ribosome prevent subsequent AUG codons from being bound by isoleucine tRNA? Do UAU anticodons simply not exist?

Thanks

Post Merge: 9 years ago

It turns out UAU anticodons do not exist in most species at all.

http://nar.oxfordjournals.org/content/early/2012/05/01/nar.gks350.full