1 / 20

Protein phosphatases

Protein phosphatases. Protein phosphatase acting as a reset button for kinases this action is either a) inactivating or b) activating. like for protein kinases, a distinction is made between tyrosine and threonine /serine phosphatases.

lucas
Download Presentation

Protein phosphatases

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Protein phosphatases

  2. Protein phosphatase acting as a reset button for kinasesthis action iseithera) inactivatingorb) activating

  3. like for protein kinases, a distinction is made between tyrosine and threonine/serine phosphatases As there is always an exception to the rule: certain phosphatases recognize both phosphotyrosine and phosphothreonine/serine residues these are the dual specificity phosphatases

  4. { serine threonine { tyrosine serine threonine tyrosine {

  5. The depth of the catalyticpocketis one of the determinants of phosphoresiduespecificity of the protein phosphatase

  6. Serine / threonine phosphatases

  7. Mechanism of action and highlyconserved (signature) sequences of serine / threonineprotein phosphatases. The catalyticsubunits have broadspecificity

  8. Specificity of serine/threonine phosphatases islargelydetermined by association of regulatorysubunitsthat affect subcellular localisation as well as substratespecificity

  9. The regulatorysubunit MYPT1 turns the broad-specificity PP1C (catalyticsubunit) into a myosinregulatory-light chain-specific phosphatase - R= arginine & K= lysine are positivelychargedresiduesthat fit the negativelychargedacidic groove - Dephosphorylation of myosinregulatorylight chaincauses smooth muscle cell relaxation (no hydrolysis of ATP)

  10. Role of the phosphatase calcineurin in antigen-mediated T-cell activation(followed by clonal expansion (adaptive immunity))

  11. the activated T-cellreceptorinduces a Ca2+ signal thatbindscalcineurin and activates the catalyticsubunit (CnA) (PP2B), leading to dephosphorylation and nuclear translocation of the transcription factor NFAT NFAT=nuclear factor of activated T-cells

  12. action of protein phosphatase

  13. tyrosine protein phosphates (PTP)

  14. twostepmechanism of action of protein tyrosine phosphatases

  15. Tyrosine phosphatase as an inactivator of insulinsignalling: tyrosine phosphatase 1B (PTP1B) dephosphorylates the insulinreceptor

  16. Certain tyrosine phosphatases have tumoursuppressorfunctions (by opposing to deragulated tyrosine protein kinases)

  17. tyrosine phosphatase as an activator of Src: dephosphorylation of the C-terminal tyrosine phosphate by CD45

  18. the SH2 domainbound to the C-terminal phosphotyrosinekeeps the kinase in an incompetent conformation dephosphorylationremovesthisconstraint and isfollowed by autophosphorylation. The kinase isnowfullycompetent

  19. PTEN qualifies by its structure and itssequence as a tyrosine phosphatase but itprefersinositollipidsand acts as a inositollipid phosphatase (important tumoursuppressorrole)

  20. PTEN removes the phosphates that have been added by PI 3-kinase PI 3-kinase isactivated by growthfactors (includinginsulin) and plays an important role in growthregulation and cellsurvival thisexplainswhyloss of PTEN isinvolved in cell transformation (cancer development)

More Related