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Phosph. signalling
Uni of Notts, Signalling & Metabolic Regulation, Year 2, Topic 3
| Term | Definition |
|---|---|
| Post-Translational Modification (PMT) | Covalent modification of proteins during or after synthesis, usually using enzymes, to give the protein new properties |
| S-nitrosylation | Reaction replacing H on thiol on a cysteine with NO to make -SNO. Switches on & off proteins like phosphorylation & affects binding. Redox sensitive & uses enzymes to regulate |
| Why phosphorylation is one of the most therapeutically significant PMTs | Kinases & phosphatases that regulate are often mutated or expressed in wrong quantities, this leads to disease. Scientists can control these disease by developing agonists & antagonists |
| Lipidation | Incorporating lipids into protein to allow their insertion into oily areas such as membranes or vesicles |
| Phosphorylation of nuclear protein transcription factors | Reversible esterification of R'-OH groups on amino acids (usually serine or threonine) to cause a conformational shape change to enter the nucleus & affect gene transcription |
| Indirect activation by phosphorylation | Activated kinase can phosphorylate residues on adaptor proteins to change conformation & make docking sites, then these bind different proteins & bring them together to allow them to activate each other |
| How phosphorylation changes cell localisation | Changes conformation, charge, & protein-protein interactions. Can expose or mask localisation sequences, repel -ve phospholipids in membranes, recruit adaptors, the cytoskeleton, & affect nuclear import/export |
| Evolutionary differences between kinases & phosphatases | Phosphatases don't share ancestral origins unlike the Kinome which comes from few ancestor genes & not well conserved but has some structural & sequential homologies |
| Functional differences between kinases & phosphatases | 100/147 phosphatases for tyrosine but most have dual specificity, they're less specific than kinases & work for a variety of targets. Don't require energy investment |
| How phosphate specificity is achieved (modularity, SLiM, regulatory subunit assisted) | They're made from interchangeable structural components that determine specificity, bind to Short Linear Motifs on IDR targets & regulators, & rely on partner proteins for specificity & localisation |
| Rb & E2f | Rb (retinoblastoma) is a tumour suppressor protein which, when hypophosphorylated, can bind & disable proliferation gene TFs to prevent cells entering S-phase, like E2f TFs which code for cyclins amongst other things |
| Rb chromatin modification | When hypophosphorylated, recruits histone deacetylases & chromatin remodelers to repress chromatin |
| Effect of growth factors on Rb & Ef2 | Upregulates cyclin D, this activates cyclin-CDK to phosphorylate Rb, this disinhibits E cyclin production which activates E2f, hyperphosphorylates Rb & locks the cell into S-phase |
| Effect of anti-growth factors on Rb | Induces CDK inhibition & suppresses cyclin B expression, shifts cells to specialised non-dividing states where Rb is permanently active. Protein Phosphatase 1 (PP1) restores Rb function |
| Rb multiple phosphorylation | Contains 14-16 CDK sites. Unphosphorylated is the most powerful mitosis suppressor. Each phosphorylation causes a different conformation & slightly weakens it until it's deactivated |
| How Human Papilloma Virus (HPV) can be carconogenic | Binds to cleft in Rb to degrade the protein which can lead to mitotic runaway & uncontrollably dividing cells |
| Ef2 structure | Dimer formed from basic DNA-activator & acidic transcriptional activator which also contains an Rb binding site to regulate it |
Created by:
Denny12
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