title: Cleavage and activation of p21-activated protein kinase gamma-PAK by CPP32 (caspase 3). Effects of autophosphorylation on activity.
abstract: p21-activated protein kinase gamma-PAK (Pak2, PAK I) is cleaved by CPP32 (caspase 3) during apoptosis and plays a key role in regulation of cell death. In vitro, CPP32 cleaves recombinant gamma-PAK into two peptides; 1-212 contains the majority of the regulatory domain whereas 213-524 contains 34 amino acids of the regulatory domain plus the entire catalytic domain. Following cleavage, both peptides become autophosphorylated with [gamma-32P]ATP. Peptide 1-212 migrates at 27,000 daltons (p27) upon SDS-polyacrylamide gel electrophoresis and at 32,000 daltons following autophosphorylation on serine (p27P); the catalytic subunit migrates at 34,000 daltons (p34) before and after autophosphorylation on threonine. Following caspase cleavage, a significant lag (approximately 5 min) is observed before autophosphorylation and activity are detected. When gamma-PAK is autophosphorylated with ATP(Mg) alone and then cleaved, only p27 contains phosphate, and the enzyme is inactive with exogenous substrate. After autophosphorylation of gamma-PAK in the presence of Cdc42(GTPgammaS) or histone 4, both cleavage products contain phosphate and gamma-PAK is catalytically active. Mutation of the conserved Thr-402 to alanine greatly reduces autophosphorylation and protein kinase activity following cleavage. Thus activation of gamma-PAK via cleavage by CPP32 is a two-step mechanism wherein autophosphorylation of the regulatory domain is a priming step, and activation coincides with autophosphorylation of the catalytic domain.
authors.affiliation: Department of Biochemistry, University of California, Riverside, Riverside, California 92521, USA.
authors.forename: B N
authors.initials: BN
authors.lastname: Walter
authors.forename: Z
authors.initials: Z
authors.lastname: Huang
authors.forename: R
authors.initials: R
authors.lastname: Jakobi
authors.forename: P T
authors.initials: PT
authors.lastname: Tuazon
authors.forename: E S
authors.initials: ES
authors.lastname: Alnemri
authors.forename: G
authors.initials: G
authors.lastname: Litwack
authors.forename: J A
authors.initials: JA
authors.lastname: Traugh
mesh_terms: D053148:Caspase 3; D020169:Caspases / Q000378:metabolism*; D020134:Catalytic Domain; D002460:Cell Line; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D006868:Hydrolysis; D010449:Peptide Mapping; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D054462:p21-Activated Kinases
chemical_list: D011994:Recombinant Proteins; D017346:Protein Serine-Threonine Kinases; D054462:p21-Activated Kinases; D053148:Caspase 3; D020169:Caspases