title: Phosphorylation of the mitochondrial protein Sab by stress-activated protein kinase 3.
abstract: Mitogen-activated protein kinases (MAPKs) transduce extracellular signals into responses such as growth, differentiation, and death through their phosphorylation of specific substrate proteins. Early studies showed the consensus sequence (Pro/X)-X-(Ser/Thr)-Pro to be phosphorylated by MAPKs. Docking domains such as the "kinase interaction motif" (KIM) also appear to be crucial for efficient substrate phosphorylation. Here, we show that stress-activated protein kinase-3 (SAPK3), a p38 MAPK subfamily member, localizes to the mitochondria. Activated SAPK3 phosphorylates the mitochondrial protein Sab, an in vitro substrate of c-Jun N-terminal kinase (JNK). Sab phosphorylation by SAPK3 was dependent on the most N-terminal KIM (KIM1) of Sab and occurred primarily on Ser321. This appeared to be dependent on the position of Ser321 within Sab and the sequence immediately surrounding it. Our results suggest that SAPK3 and JNK may share a common target at the mitochondria and provide new insights into the substrate recognition by SAPK3.
authors.affiliation: Cell Signalling Laboratory, Biochemistry and Molecular Biology, University of Western Australia, Crawley, Western Australia 6009, Australia.
authors.forename: Naomi W
authors.initials: NW
authors.lastname: Court
authors.forename: Ivana
authors.initials: I
authors.lastname: Kuo
authors.forename: Oonagh
authors.initials: O
authors.lastname: Quigley
authors.forename: Marie A
authors.initials: MA
authors.lastname: Bogoyevitch
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D020935:MAP Kinase Signaling System; D008928:Mitochondria / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048291:Mitogen-Activated Protein Kinase 12; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D032383:Myocytes, Cardiac / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D051381:Rats; D012694:Serine / Q000737:chemistry; D013379:Substrate Specificity
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; C112230:SH3BP5 protein, human; D012694:Serine; D005982:Glutathione Transferase; D048291:Mitogen-Activated Protein Kinase 12; D048031:JNK Mitogen-Activated Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D020928:Mitogen-Activated Protein Kinases