During the protein formation methionine always binds first in any type of protein with the large subunit of the ribosome; what could be the possible reasons, can anybody explain it?
Usually, the first codon in the protein-coding sequence is AUG, which codes for methionine in eukaryotes. However, even in the unusual cases when the first codon is not AUG, methionine is still incorporated because a special initiator tRNA charged with methionine is used to start translation.
http://www.els.net/WileyCDA/ElsArticle/refId-a0000543.html
Whereas this explains how Met ends up at the N-terminus in eukaryotes (formyl-Met in prokaryotes), it does not explain why. This is probably a system that developed very early in biological evolution along with the genetic code and ribosomes.
The N-terminal Met or f-Met is often removed, so that the finished protein does not have Met at the N-terminus.
Because the first tRNA to bind to the peptidyl binding site (P site) in the initiation complex is always the initiator tRNA, tRNAfMET. tRNAfMET binds to the start codon of mRNA, AUG. The first amino acid of the protein is thus methionine.
- Badges
- Science topic
- Similar topics
- Biological Science
- Molecular Biology