Comprehending Post Translational Modifications

November 12, 2012

Comprehending Post Translational Modifications

Post translational changes take place to recently formed proteins and play an important role in whether or not cells function as they should in different parts of the body.

The inner workings of cell is extraordinary when a person takes into account all the things that has to happen in a certain amount of time and in just right the way in order to ensure that proteins get to the right place and the right time to be productive. DNA is transcribed into messenger RNA which is than translated into a sequence of amino acids. This sequence will determine the structure and type of protein made by the cell. Post translational modifications occur after a protein has been created. The modifications are chemical in nature and can severely alter the function of a protein.

Importance of Protein Changes

The most important reason for post translational protein changes is that they are necessary for functionality. These chemical alterations make it possible for humans and other animals to use the same basic protein for a multitude of functions. Without these modifications, the heterogeneity of proteins would not exist. The addition of different functional groups will determine how each protein sequence will act within its target cell. An example of this is the modification that takes place at the peptide end of a protein which makes it possible for the protein to move across different biological membranes. Essentially, if the correct post translational change does not take place, the protein may not be expressed accurately. Inadequate or faulty protein expression can cause a number of disease conditions associated with the inability of enzymes, cells, and even the body to function at its maximum potential. Protein expression problems can cause mild to terminally ill states.

Methods for Post Translational Modifications

The cellular system in all animals has found a multitude of ways to make proteins work to their advantage. The post translational changes make it possible for them to utilize a set of proteins for multiple functions. The changes themselves can take place in a number of the following ways:

  • Lipoylation- when a lipoate function group is attached to the protein

  • Phosphorylation- phosphate group is added to a protein at either the tyrosine, serine, or histodine amino acid

  • Acetylation- this is when an acetyl functional group is added to the N-terminus

  • Glycosylation- the addition of a carbohydrate group which normally occurs in eukaryotic cells

  • Glutamylation- covalent bond formed between tubulin and glutamic acid residue

  • Isoprenylation- an isoprenoid group is added to the protein

  • Methylation- a type of acetylation where a methyl group is added

  • Sulfation- sulfate group added to the amino acid tyrosine

  • Biotinylation- Lysine residues undergo acylation with biotin appendages

  • Glycylation- covalent linkage between a number of glycine residues to the C-terminal of an amino acid

  • C-terminal amidation

The post translational changes can occur in a variety of ways and each method has a different effect. These modifications can be seen in almost all prokaryotic and eukaryotic cells.


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