title: Properties of the co-chaperone protein p23 erroneously attributed to ALG-2 (apoptosis-linked gene 2).
abstract: A commercial antibody (clone 22) directed against the apoptosis-linked gene 2 (alg2, pdcd6) encoded protein has been used by several groups. Up-regulated expression of the antigen was observed in primary tumours and in metastatic tissue and also during rat brain ischemia. Furthermore, antigen down-regulation was found in human atherosclerotic plaques. Recently, we found that the clone 22 antibody does not recognise ALG-2. In the present study the antigen of the clone 22 antibody was identified as the heat shock protein 90 (HSP90) co-chaperone protein p23, identical to the cytosolic prostaglandin E2 synthase, by immunoprecipitation followed by tryptic in-gel digests and mass spectrometry of the purified peptides. Moreover, the heterogeneous ribonuclear protein A2/B1 was found to be a part of the p23 co-immunoprecipitated protein complex.
authors.affiliation: Department of Molecular Cell Biology, Institute of Molecular Biology, University of Copenhagen, Øster Farimagsgade 2A, 1353 Copenhagen K, Denmark. jmollerup@my.molbio.ku.dk
authors.forename: Jens
authors.initials: J
authors.lastname: Mollerup
authors.forename: Thomas N
authors.initials: TN
authors.lastname: Krogh
authors.forename: Per F
authors.initials: PF
authors.lastname: Nielsen
authors.forename: Martin W
authors.initials: MW
authors.lastname: Berchtold
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D002135:Calcium-Binding Proteins / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism*; D003001:Cloning, Molecular; D005786:Gene Expression Regulation; D006801:Humans; D019746:Intramolecular Oxidoreductases; D019169:Jurkat Cells; D051379:Mice; D018832:Molecular Chaperones / Q000737:chemistry* / Q000378:metabolism*; D010446:Peptide Fragments / Q000032:analysis / Q000235:genetics; D010750:Phosphoproteins / Q000737:chemistry* / Q000378:metabolism*; D011233:Precipitin Tests; D000071876:Prostaglandin-E Synthases; D051381:Rats; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods; D019014:fas Receptor / Q000276:immunology
chemical_list: D000906:Antibodies; D051017:Apoptosis Regulatory Proteins; D002135:Calcium-Binding Proteins; D018832:Molecular Chaperones; C097753:PDCD6 protein, human; C490815:Pdcd6 protein, mouse; D010446:Peptide Fragments; D010750:Phosphoproteins; D011994:Recombinant Proteins; D019014:fas Receptor; D019746:Intramolecular Oxidoreductases; C490849:PTGES3 protein, human; D000071876:Prostaglandin-E Synthases; C000605868:Ptges3 protein, mouse