Everything about Formylmethionine totally explained
N-Formylmethionine(fMet) is an
amino acid found in all living
cells. It is a derivative of the
amino acid methionine. It is a modified form of
methionine in which a
formyl group has been added to methionine's
amino group.
It plays a crucial part in the
protein synthesis of
bacteria,
mitochondria and
chloroplasts. It isn't used in the
protein synthesis taking place in the
cytosol of
eukaryotes, where
eukaryotic nuclear genes are
translated.
Function in protein synthesis
fMet is a starting residue in the synthesis of
proteins in
prokaryotes and, consequently, is located at the N-terminus of the growing
polypeptide. fMet is delivered to the
ribosome (30S) - mRNA complex by a specialized
tRNA (tRNA.fMet) which has a 5'-CAU-3'
anticodon that's capable of binding with the AUG start
codon located on the
mRNA.
N-Formylmethionine is coded by the same
codon as
methionine, AUG. However, AUG is also the
translation initiation
codon. When the codon is used for initiation, N-formylmethionine is used instead of
methionine, thereby forming the first
amino acid of the nascent
peptide chain. When the same
codon appears later in the
mRNA, normal
methionine is used. Many organisms use variations of this basic mechanism.
The addition of the formyl group to methionine is catalyzed by the
enzyme transformylase. This modification is done after methionine has been loaded onto tRNA.fMet by
aminoacyl-tRNA synthetase.
Note that methionine can be loaded either onto tRNA.fMet or tRNA.Met. Transformylase will catalyze the addition of the formyl group to methionine only if methionine has been loaded onto tRNA.fMet and NOT onto tRNA.Met.
Relevance to immunology
Because N-Formylmethionine is present in proteins made by
prokaryotes but not in those made by
eukaryotes, the
immune system can use it to help distinguish self from non-self.
Polymorphonuclear cells can bind proteins starting with N-Formylmethionine, and use them to initiate
phagocytosis.
Further Information
Get more info on 'Formylmethionine'.
|
External Link Exchanges
Do you know how hard it is to get a link from a large encyclopaedia? Well we're different and will prove it. To get a link from us just add the following HTML to your site on a relevant page:
<a href="http://n-formylmethionine.totallyexplained.com">N-Formylmethionine Totally Explained</a>
Then simply click through this link from your web page. Our crawlers will verify your link, extract the title of your web page and instantly add a link back to it. If you like you can remove the words Totally Explained and embed the link in article text.
As long as your link remains in place, we'll keep our link to you right here. Please play fair - our crawlers are watching. Your site must be closely related to this one's topic. Any kind of spamming, dubious practises or removing the link will result in your link from us being dropped and, potentially, your whole site being banned. |
