| Structural highlights
Function
PAK4_HUMAN Serine/threonine protein kinase that plays a role in a variety of different signaling pathways including cytoskeleton regulation, cell migration, growth, proliferation or cell survival. Activation by various effectors including growth factor receptors or active CDC42 and RAC1 results in a conformational change and a subsequent autophosphorylation on several serine and/or threonine residues. Phosphorylates and inactivates the protein phosphatase SSH1, leading to increased inhibitory phosphorylation of the actin binding/depolymerizing factor cofilin. Decreased cofilin activity may lead to stabilization of actin filaments. Phosphorylates LIMK1, a kinase that also inhibits the activity of cofilin. Phosphorylates integrin beta5/ITGB5 and thus regulates cell motility. Phosphorylates ARHGEF2 and activates the downstream target RHOA that plays a role in the regulation of assembly of focal adhesions and actin stress fibers. Stimulates cell survival by phosphorylating the BCL2 antagonist of cell death BAD. Alternatively, inhibits apoptosis by preventing caspase-8 binding to death domain receptors in a kinase independent manner. Plays a role in cell-cycle progression by controlling levels of the cell-cycle regulatory protein CDKN1A and by phosphorylating RAN.[1] [2] [3] [4] [5] [6] [7]
Publication Abstract from PubMed
The type II p21-activated kinases (PAKs) are key effectors of RHO-family GTPases involved in cell motility, survival, and proliferation. Using a structure-guided approach, we discovered that type II PAKs are regulated by an N-terminal autoinhibitory pseudosubstrate motif centered on a critical proline residue, and that this regulation occurs independently of activation loop phosphorylation. We determined six X-ray crystal structures of either full-length PAK4 or its catalytic domain, that demonstrate the molecular basis for pseudosubstrate binding to the active state with phosphorylated activation loop. We show that full-length PAK4 is constitutively autoinhibited, but mutation of the pseudosubstrate releases this inhibition and causes increased phosphorylation of the apoptotic regulation protein Bcl-2/Bcl-X(L) antagonist causing cell death and cellular morphological changes. We also find that PAK6 is regulated by the pseudosubstrate region, indicating a common type II PAK autoregulatory mechanism. Finally, we find Src SH3, but not beta-PIX SH3, can activate PAK4. We provide a unique understanding for type II PAK regulation.
Type II p21-activated kinases (PAKs) are regulated by an autoinhibitory pseudosubstrate.,Ha BH, Davis MJ, Chen C, Lou HJ, Gao J, Zhang R, Krauthammer M, Halaban R, Schlessinger J, Turk BE, Boggon TJ Proc Natl Acad Sci U S A. 2012 Sep 17. PMID:22988085[8]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Gnesutta N, Qu J, Minden A. The serine/threonine kinase PAK4 prevents caspase activation and protects cells from apoptosis. J Biol Chem. 2001 Apr 27;276(17):14414-9. Epub 2001 Jan 24. PMID:11278822 doi:10.1074/jbc.M011046200
- ↑ Qu J, Cammarano MS, Shi Q, Ha KC, de Lanerolle P, Minden A. Activated PAK4 regulates cell adhesion and anchorage-independent growth. Mol Cell Biol. 2001 May;21(10):3523-33. PMID:11313478 doi:10.1128/MCB.21.10.3523-3533.2001
- ↑ Gnesutta N, Minden A. Death receptor-induced activation of initiator caspase 8 is antagonized by serine/threonine kinase PAK4. Mol Cell Biol. 2003 Nov;23(21):7838-48. PMID:14560027
- ↑ Soosairajah J, Maiti S, Wiggan O, Sarmiere P, Moussi N, Sarcevic B, Sampath R, Bamburg JR, Bernard O. Interplay between components of a novel LIM kinase-slingshot phosphatase complex regulates cofilin. EMBO J. 2005 Feb 9;24(3):473-86. Epub 2005 Jan 20. PMID:15660133 doi:7600543
- ↑ Li Z, Zhang H, Lundin L, Thullberg M, Liu Y, Wang Y, Claesson-Welsh L, Stromblad S. p21-activated kinase 4 phosphorylation of integrin beta5 Ser-759 and Ser-762 regulates cell migration. J Biol Chem. 2010 Jul 30;285(31):23699-710. doi: 10.1074/jbc.M110.123497. Epub, 2010 May 27. PMID:20507994 doi:10.1074/jbc.M110.123497
- ↑ Bompard G, Rabeharivelo G, Frank M, Cau J, Delsert C, Morin N. Subgroup II PAK-mediated phosphorylation regulates Ran activity during mitosis. J Cell Biol. 2010 Sep 6;190(5):807-22. doi: 10.1083/jcb.200912056. Epub 2010 Aug , 30. PMID:20805321 doi:10.1083/jcb.200912056
- ↑ Wallace SW, Durgan J, Jin D, Hall A. Cdc42 regulates apical junction formation in human bronchial epithelial cells through PAK4 and Par6B. Mol Biol Cell. 2010 Sep 1;21(17):2996-3006. doi: 10.1091/mbc.E10-05-0429. Epub, 2010 Jul 14. PMID:20631255 doi:10.1091/mbc.E10-05-0429
- ↑ Ha BH, Davis MJ, Chen C, Lou HJ, Gao J, Zhang R, Krauthammer M, Halaban R, Schlessinger J, Turk BE, Boggon TJ. Type II p21-activated kinases (PAKs) are regulated by an autoinhibitory pseudosubstrate. Proc Natl Acad Sci U S A. 2012 Sep 17. PMID:22988085 doi:http://dx.doi.org/10.1073/pnas.1214447109
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