title: The endogenous substrate of low molecular weight acid phosphatase in the brain is an epidermal growth factor receptor.
abstract: We have recently reported that low molecular weight (LMW) acid phosphatase, which is supposed to possess phosphotyrosine protein phosphatase activity, showed a significant decrease of activity in Alzheimer brains compared to control brains [Ann. Neurol., 33 (1993) 616-621]. In the present study, we investigated the endogenous substrate of LMW acid phosphatase in the brain. LMW acid phosphatase was purified from bovine brain, and the enzyme was obtained with both a high specific activity and a good yield. The bovine brain enzyme was a monomer with a molecular mass of 17 kDa. We used a specific monoclonal anti-phosphotyrosine antibody to detect phosphotyrosine protein in rat brain extracts. The LMW acid phosphatase from bovine brain dephosphorylated a M(r) 170 kDa phosphotyrosine protein in rat brain extracts. This M(r) 170 kDa protein was considered to be the epidermal growth factor (EGF) receptor using a specific antibody. These results suggest that LMW acid phosphatase in the brain may regulate EGF receptor-dependent transmembrane signalling by dephosphorylating the phosphorylated receptor.
authors.affiliation: Department of Neurology, Faculty of Medicine, Kyoto University, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Shimohama
authors.forename: S
authors.initials: S
authors.lastname: Fujimoto
authors.forename: T
authors.initials: T
authors.lastname: Taniguchi
authors.forename: J
authors.initials: J
authors.lastname: Kimura
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000201:enzymology; D001923:Brain Chemistry / Q000502:physiology*; D002417:Cattle; D066246:ErbB Receptors / Q000378:metabolism*; D007120:Immunochemistry; D008970:Molecular Weight; D010766:Phosphorylation; D019000:Phosphotyrosine; D051381:Rats; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D019000:Phosphotyrosine; D014443:Tyrosine; D066246:ErbB Receptors; D000135:Acid Phosphatase