Post-translational modification
Covalent protein changes after synthesis, diversifying function beyond transcription.
Post-translational modifications (PTMs) are the covalent processes of changing proteins following their synthesis and release from ribosomes. They are reversible editing events used in post-translational regulation, the control of the levels of active protein, and enable a protein's function to be diversified and extended beyond the dictates of transcription.
- field
- Biochemistry, molecular biology
- known_for
- Covalent modification of proteins after translation, expanding protein function beyond genetic code
- common_modification
- Phosphorylation
- detection_methods
- Mass spectrometry, Eastern blotting, Western blotting
Lore & Background
Post-translational modifications (PTMs) involve enzymes or occur spontaneously. Proteins are created by ribosomes, which translate mRNA into polypeptide chains, which may then change to form the mature protein product, released from the ribosome. PTMs are important components in cell signaling, as when prohormones are converted to hormones. They can occur on amino acid side chains or at the protein's C- or N-termini, expanding the chemical set of the 22 amino acids by changing an existing functional group or adding a new one such as phosphate.
Reader's Guide
Post-translational modifications are fundamental to cellular regulation, enabling rapid, reversible control of protein activity without altering gene expression. Phosphorylation is the most common change after translation and is highly effective for controlling enzyme activity. Glycosylation, the attachment of carbohydrate molecules, promotes protein folding and improves stability as well as serving regulatory functions. Lipidation often targets a protein to the cell membrane. PTMs also include cleaving peptide bonds, as in processing a propeptide to a mature form, and disulfide bond formation. Some PTMs, like carbonylation, are consequences of oxidative stress and can target proteins for degradation or form aggregates. PTMs and metal ions play a crucial reciprocal role in regulating protein function, influencing signal transduction and gene expression, with dysregulated interactions implicated in diseases like cancer and neurodegenerative disorders. Sites that often undergo PTM include the hydroxyl groups of serine, threonine, and tyrosine; the amine forms of lysine, arginine, and histidine; the thiolate anion of cysteine; the carboxylates of aspartate and glutamate; and the N- and C-termini. Detection is achieved via mass spectrometry, Eastern blotting, and Western blotting.
Did You Know?
- Phosphorylation is the most common change after translation.
- PTMs are also prokaryotic processes.
- Carbonylation is a PTM that can result in the formation of protein aggregates.
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