AH Biology: Unit 1 Protein Structure 3

1. AH Biology: Unit 1Protein Structure 3 Reversible Binding of Phosphate and Control of Conformation

2. Reversible binding of phosphate and control of conformation LOS • The additional or removal of phosphate from particular R groups can be used to cause reversible conformational changes in proteins. This is a common form of post-transitional modification. • This is how many cellular proteins such as enzymes and receptors are regulated. • Kinase is often responsible for phosphorylation of other proteins and phosphatase catalyses dephosphorylation.

3. Reversible binding of phosphate and control of conformation LOS 2 • Some proteins (ATPases) use ATP for their phosphorylation. • Myosin has heads that act as crossbridges as they bind to actin. When ATP binds to myosin, the myosin head detaches from actin, swings forwards and rebinds. • The rebinding releases the ADP and a phosophate ion drags the myosin along the actin filament.

4. Think • What conditions are affected by the permanent activation of specific proteins? • What is the charge on a phosphate group? • What effect does phosphate have on protein? • How is ATP generated by a cell? • How is ATP used by a cell?

5. Kinase • Kinase is often responsible for the phosphorylation of other proteins through ATP.

6. Kinase • A phosphate group is highly charged, altering the position of charged bonding in the three-dimensional structure of the protein and as a result causing a conformational change.

7. Kinase • Kinase animation 1 • Kinase animation 2

8. Kinase • Now read this article: • Knight JDR, Qian B, Baker D, Kothary R (2007) Conservation, Variability and the Modeling of Active Protein Kinases. PLoS ONE 2(10): e982. doi:10.1371/journal.pone.0000982 • Use Proteomics Tutorial 1 and answer the targeted questions in relation to this article.

9. Phosphatase • Phosphatase catalyses dephosphorylation of other proteins by the hydrolysis of phosphate from the protein molecule. • This again changes the conformation of the protein as a result of charge interactions of the R groups in the protein.

10. Signal transduction • Extracellular hydrophilic signalling molecules are involved in the activation of extracellular receptor proteins that then interact with intracellular proteins through a series of kinases and phosphatases. • This cascade of phosphorylation and dephosphorylation quickly activates intracellular events. • Insulin and the blood sugar level are controlled in this way, as is cell death (apoptosis). • G-protein-coupled signal transduction • Cyclic AMP signalling

11. Kinase cascade

12. Sodium potassium pump

13. ATPases • Some proteins such as ATPases use ATP for their phosphorylation. • Sodium potassium pump animation • Glucose co-transporter animation

14. Mitochondria

15. Aerobic respiration

16. Skeletal/striated muscle and contraction using ATP

17. ATP and muscle contraction • A muscle contracts as the actin and myosin filaments slide past each other. • Myosin has heads act as cross bridges as they bind to actin at specific binding sites and allow the muscle to contract. • Sarcomere contraction animation

18. ATP and muscle contraction • When actin binds to myosin, the myosin head detaches from actin, swings forwards and rebinds. The rebinding releases the ADP and a phosphate ion drags the myosin along the actin filament.

19. Transmission electron microscope image: human striated muscle

20. Muscle contraction via ATPase • Breakdown of ATP and cross-bridge movement animation. • Actin and myosin animation • Actin and myosin animation: Harvard BioVisions in detail

21. Reversible binding of phosphate and control of conformation LOS • The addition or removal of ________ from particular R groups can be used to cause _________ ________ changes in proteins. This is a common form of ____________ modification. • This is how many cellular proteins such as _______ and ________ are regulated. • _______ is often responsible for phosphorylation of other proteins and __________ catalyses dephosphorylation.

22. Reversible binding of phosphate and control of conformation LOS 2 • Some proteins (_________) use ATP for their phosphorylation. • _______ has heads that act as crossbridges as they bind to _____. When ATP binds to myosin, the myosin _____ detaches from actin, swings forwards and rebinds. • The rebinding releases the _____ and a ________ ion drags the ______ along the _____ filament.

23. Reversible binding of phosphate and control of conformation • The addition or removal of phosphate from particular R groups can be used to cause reversible conformational changes in proteins. This is a common form of post-translational modification. • This is how many cellular proteins such as enzymes and receptors are regulated. • Kinase is often responsible for phosphorylation of other proteins and phosphatase catalyses dephosphorylation.

24. Reversible binding of phosphate and control of conformation • Some proteins (ATPases) use ATP for their phosphorylation. • Myosin has heads that act as crossbridges as they bind to actin. When ATP binds to myosin, the myosin head detaches from actin, swings forwards and rebinds. • The rebinding releases the ADP and a phosophate ion drags the myosin along the actin filament.

25. Think • What conditions are affected by the permanent activation of specific proteins? • What is the charge on a phosphate group? • What effect does phosphate have on protein? • How is ATP generated by a cell? • How is ATP used by a cell?