PMTs

• What are post translational modifications (PMTs)?


  Chemical modifications to proteins after translation, that can trigger an action at specific steps in the cell cycle or allow the protein to perform a precise function
• what are the 2 types of PMTs?


  -Proteolytic cleavage of subunits, or degradation of entire proteins-Covalent addition: phosphorylation, methylation, acetylation, ubiquitination, glycosylation
• how are proteins synthesised after the ribosome to mature and become functional


  1)folding into 3D shape 2)associate to other proteins (e.g dimers) 3)undergo PMTs
• Co-translationally vs Post-translationally modifications

  co- as the protein is spooled-out of the ribosome, contributing to the protein folding process. post- after the translation is concluded (after folding)
• how is insulin activated via PMTs


  (long)inactive precursor of insulin- proinsulin undergoes proteolytic cleavage
• 2 types of degradation

  lysosomal, ATP-dependent cytoplasmic (Ub-proteosome pathway)
• Phosphorylation (enzymes involved in removal/ addition and function)

  adding phosphate group via kinase (removed via phosphatases). Alters charge, shape and dynamics activating like on/off switch

  (S,T,Y)
• What is acetylation and what does it do

  regulates gene expression by adding acetyl group (from donor acetyl CoA), changes charge (acetylation by KAT, deacetylation by HDACs) (to lysine. K)
• What is methylation and what does it do

  targets histone proteins to regulate gene expression, changes charge (SAM adds (to K, R)
• what are S-Nitrosylation and lipidation


  covalent attachment of nitrogen monoxide (NO)

  addition of lipid
• PTMs are not template-driven (not genetically encoded) yet the levels of expression of the enzymes that catalyze these modifications can determine up/down regulation of PTMs, altering protein functions in health and disease