title: Modulation of the eukaryotic initiation factor 2 alpha-subunit kinase PERK by tyrosine phosphorylation.
abstract: The endoplasmic reticulum (ER)-resident protein kinase PERK attenuates protein synthesis in response to ER stress through the phosphorylation of translation initiation factor eIF2alpha at serine 51. ER stress induces PERK autophosphorylation at several serine/threonine residues, a process that is required for kinase activation and phosphorylation of eIF2alpha. Herein, we demonstrate that PERK also possesses tyrosine kinase activity. Specifically, we show that PERK is capable of autophosphorylating on tyrosine residues in vitro and in vivo. We further show that tyrosine 615, which is embedded in a highly conserved region of the kinase domain of PERK, is essential for autocatalytic activity. That is, mutation of Tyr-615 to phenylalanine compromises the autophosphorylation capacity of PERK and the phosphorylation of eIF2alpha in vitro and in vivo. The Y615F mutation also impairs the ability of PERK to induce translation of ATF4. Immunoblot analyses with a phosphospecific antibody confirm the phosphorylation of PERK at Tyr-615 both in vitro and in vivo. Thus, our data classify PERK as a dual specificity kinase whose regulation by tyrosine phosphorylation contributes to its optimal activation in response to ER stress.
authors.affiliation: Lady Davis Institute for Medical Research, McGiIl University, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, H3T 1E2 Canada.
authors.forename: Qiaozhu
authors.initials: Q
authors.lastname: Su
authors.affiliation: Lady Davis Institute for Medical Research, McGiIl University, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, H3T 1E2 Canada.
authors.forename: Shuo
authors.initials: S
authors.lastname: Wang
authors.affiliation: Lady Davis Institute for Medical Research, McGiIl University, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, H3T 1E2 Canada.
authors.forename: Hong Qing
authors.initials: HQ
authors.lastname: Gao
authors.affiliation: Lady Davis Institute for Medical Research, McGiIl University, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, H3T 1E2 Canada.
authors.forename: Shirin
authors.initials: S
authors.lastname: Kazemi
authors.affiliation: Skirball Institute, New York University School of Medicine, New York, New York 10016.
authors.forename: Heather P
authors.initials: HP
authors.lastname: Harding
authors.affiliation: Skirball Institute, New York University School of Medicine, New York, New York 10016.
authors.forename: David
authors.initials: D
authors.lastname: Ron
authors.affiliation: Lady Davis Institute for Medical Research, McGiIl University, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, H3T 1E2 Canada. Electronic address: antonis.koromilas@mcgill.ca.
authors.forename: Antonis E
authors.initials: AE
authors.lastname: Koromilas
mesh_terms: D000818:Animals; D019556:COS Cells; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D004591:Electrophoresis, Polyacrylamide Gel; D004721:Endoplasmic Reticulum / Q000378:metabolism; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D051379:Mice; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010766:Phosphorylation; D010957:Plasmids / Q000235:genetics; D014176:Protein Biosynthesis; D012694:Serine / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism*; D019892:eIF-2 Kinase / Q000235:genetics / Q000378:metabolism*
chemical_list: D015852:Eukaryotic Initiation Factor-2; D012694:Serine; D014443:Tyrosine; D019892:eIF-2 Kinase