Protein phosphorylation

• What are post-translation modification?

  covalent attachment of other molecules to proteins after synthesis
• types of post-translation modificatio:

  • phosphorylation
  • acetylation
  • methylation
• What group does phosphorulation occur on?

  OH groups of Ser, Thr and Tyr
• types of Kinases:

  • serine/threonine kinase
  • Tyrosine kinase
• What is the conformational change of phosphorylation?

  addition of a phosphate group adds 2 negative charges to the protein

  alters electrostatic interactions
• how do phosphorylation interaction affect electrostatic interaction?

  Within the protein - conformational change

  with substrate and regulatory ligands
• what state is the phosphate in?

  active state (relaxed state)
• what does glycogen synthase do ?

  N- and C- terminal phosphorylation of glyogen synthase increases negative charge
• what is nitrate reductase (NR) regulated by?

  Light
• what is proteolytic activation?

  • permanent activation mechanism
  • Many enzyme are converted from inactive precursors into active enzymes
• what are some inactive precursor?

  Zymogens or proenzymes
• how are inactive precursors activated?

  by specific cleavage of one or more peptide bonds
• Chymotrypsinogen:

  • disulphide bridges are added to keep the protein fragments from falling apart
• what occurs when you remove Ile16?

  hydrophobic and oxyanion cavities form
• How are blood clots formed?

  a product of a cascade of zymogen activation
• what do cascades allow?

  amplification of initial weak signals into rapid and large response
• what are the 2 blood clotting responses?

  intrinsic response and extrinsic respose
• what is the intrinsic response?

  Exposed surfaces of damaged blood vessels
• what is the extrinsic response?


  Factor released from damaged tissues
• What are blood clots formed from?

  fibrin
• how is fibrin formed?


  from fibrinogen by action of thrombin
• What does thrombin remove?

  A and B fibrinopeptides
• how does polymerisation of fibrin occur into protofibrils?

  Beta protein docks to Beta globular regions to form cross-link protofibrils
• what does the removal of A and B fibrinopeptides expose?

  docking sites onto globular domains