title: Stability of checkpoint kinase 2 is regulated via phosphorylation at serine 456.
abstract: Checkpoint kinase 2 (Chk2), a DNA damage-activated protein kinase, is phosphorylated at Thr-68 by ataxia telangiectasia mutated leading to its activation by phosphorylation at several additional sites. Using mass spectrometry we identified a new Chk2 phosphorylation site at Ser-456. We show that phosphorylation of Ser-456 plays a role in the regulation of Chk2 stability particularly after DNA damage. Mutation of Ser-456 to alanine results in hyperubiquitination of Chk2 and dramatically reduced Chk2 stability. Furthermore, cells expressing S456A Chk2 show a reduction in the apoptotic response to DNA damage. These findings suggest a mechanism for stabilization of Chk2 in response to DNA damage via phosphorylation at Ser-456 and proteasome-dependent turnover of Chk2 protein via dephosphorylation of the same residue.
authors: Department of Biological Sciences, Columbia University, New York, New York, 10027 and Cell Signaling Technology, Inc., Danvers, Massachusetts 01923.
authors: Elizabeth M
authors: EM
authors: Kass
authors: Jinwoo
authors: J
authors: Ahn
authors: Tomoaki
authors: T
authors: Tanaka
authors: William A
authors: WA
authors: Freed-Pastor
authors: Susan
authors: S
authors: Keezer
authors: Carol
authors: C
authors: Prives
mesh_terms: D000595:Amino Acid Sequence; D017209:Apoptosis; D045744:Cell Line, Tumor; D002469:Cell Separation; D064447:Checkpoint Kinase 2; D004249:DNA Damage; D005434:Flow Cytometry; D006801:Humans; D013058:Mass Spectrometry; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D009154:Mutation; D010766:Phosphorylation; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D012694:Serine / Q000737:chemistry*
chemical_list: D012694:Serine; D064447:Checkpoint Kinase 2; C578634:CHEK2 protein, human; D017346:Protein Serine-Threonine Kinases; D046988:Proteasome Endopeptidase Complex