title: Determinants for activation of the atypical AGC kinase Greatwall during M phase entry.
abstract: The atypical AGC kinase Greatwall (Gwl) mediates a pathway that prevents the precocious removal of phosphorylations added to target proteins by M phase-promoting factor (MPF); Gwl is thus essential for M phase entry and maintenance. Gwl itself is activated by M phase-specific phosphorylations that are investigated here. Many phosphorylations are nonessential, being located within a long nonconserved region, any part of which can be deleted without effect. Using mass spectrometry  and mutagenesis, we have identified 3 phosphorylation sites (phosphosites) critical to Gwl activation (pT193, pT206, and pS883 in Xenopus laevis) located in evolutionarily conserved domains that differentiate Gwl from related kinases. We propose a model in which the initiating event for Gwl activation is phosphorylation by MPF of the proline-directed sites T193 and T206 in the presumptive activation loop. After this priming step, Gwl can intramolecularly phosphorylate its C-terminal tail at pS883; this site probably plays a role similar to that of the tail/Z motif of other AGC kinases. These events largely (but not completely) explain the full activation of Gwl at M phase.
authors.affiliation: Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, USA.
authors.forename: Kristina A
authors.initials: KA
authors.lastname: Blake-Hodek
authors.forename: Byron C
authors.initials: BC
authors.lastname: Williams
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhao
authors.forename: Priscila V
authors.initials: PV
authors.lastname: Castilho
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.forename: Yuxin
authors.initials: Y
authors.lastname: Mao
authors.forename: Tomomi M
authors.initials: TM
authors.lastname: Yamamoto
authors.forename: Michael L
authors.initials: ML
authors.lastname: Goldberg
mesh_terms: D000818:Animals; D020134:Catalytic Domain; D002460:Cell Line; D004789:Enzyme Activation; D013058:Mass Spectrometry; D016200:Maturation-Promoting Factor / Q000378:metabolism; D008938:Mitosis / Q000502:physiology*; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D011392:Proline; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D029867:Xenopus Proteins / Q000737:chemistry / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D029867:Xenopus Proteins; D011392:Proline; C544010:MASTL protein, Xenopus; D017346:Protein Serine-Threonine Kinases; D016200:Maturation-Promoting Factor