Summary
Chemical changes such as phosphorylation, glycosylation and ubiquitination that regulate protein activity and fate.
In depth
Phosphorylation by kinases switches proteins on or off, glycosylation helps folding and targeting, acetylation and methylation regulate histones, and ubiquitination marks proteins for degradation. Proteolytic cleavage activates others, such as insulin from proinsulin.
A single protein can have many modification sites forming a regulatory code.
Over 200 types are known. Phosphorylation occurs on serine, threonine and tyrosine, adds a negative charge and acts as a reversible switch; roughly a third of human proteins are phosphorylated. Ubiquitin chains of four or more mark proteins for the proteasome, whereas a single ubiquitin may signal other things.
Proteolytic processing also activates proteins: insulin is made as preproinsulin and cut to its active form, and digestive enzymes are made as inactive zymogens (trypsinogen) to avoid self-digestion. Lipid attachments, such as farnesylation of Ras, anchor proteins to membranes.
Example: histone acetylation loosens chromatin and generally promotes gene activity, making modification a regulatory code.
Frequently asked questions
What is Protein Post-Translational Modification?
Chemical changes such as phosphorylation, glycosylation and ubiquitination that regulate protein activity and fate.
Which area of biology covers Protein Post-Translational Modification, and how advanced is it?
Protein Post-Translational Modification is one of the 51 topics in Biomolecules & Biochemistry. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Allosteric Regulation, Denaturation, Amino Acids.
Can you give an example of Protein Post-Translational Modification?
P53 is stabilised by phosphorylation after DNA damage.
What should I learn before Protein Post-Translational Modification?
Work through the Beginner topics in Biomolecules & Biochemistry first, such as Water Properties, Carbon Chemistry, Carbohydrates, then return to Protein Post-Translational Modification. Advanced topics assume the Intermediate vocabulary.
What topics are related to Protein Post-Translational Modification?
The closest topics to Protein Post-Translational Modification are Allosteric Regulation, Denaturation, Amino Acids, Proteins. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Protein Post-Translational Modification?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Protein Post-Translational Modification. To practise the whole of Biomolecules & Biochemistry, use the Biomolecules & Biochemistry quiz.
How is Protein Post-Translational Modification different from Allosteric Regulation?
Protein Post-Translational Modification: Chemical changes such as phosphorylation, glycosylation and ubiquitination that regulate protein activity and fate. Allosteric Regulation: Binding of a molecule at a site other than the active site changes enzyme shape and activity. Read both side by side and note what each one explains.
How should I study Protein Post-Translational Modification step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Allosteric Regulation and explain the difference aloud. Finally, take the Biomolecules & Biochemistry quiz and come back to this page for any question you miss.