In this paper we demonstrate that the cytosolic low-Mr acid phosphatase purified from bovine liver has phosphotyrosine protein phosphatase activity on 32P-autophosphorylated epidermal growth factor (EGF) receptor. This activity was significantly inhibited by orthovanadate and p-hydroxymercuribenzoate; the latter result indicates that free sulfhydryl groups are required for phosphotyrosine phosphatase activity. The enzyme was active in a broad pH range, with maximum activity between pH 5.5 and 7.5. The apparent Km for 32P-EGF receptor dephosphorylation was 4 nM. The enzyme appeared to be specific for phosphotyrosine in that it dephosphorylated the autophosphorylated EGF receptor and L-phosphotyrosine, but not 32P-Ser-casein, L-phosphoserine or L-phosphothreonine. These data suggest that the cytosolic low-Mr acid phosphatase might play a regulatory role in EGF receptor-dependent transmembrane signalling.

The 18 kDa cytosolic acid phosphatase from bovine liver has phosphotyrosine phosphatase activity on the auto phosphorylated epidermal grwth factor receptor / G. RAMPONI ; G. MANAO ; G. CAMICI ; G. CAPPUGI; M. RUGGIERO ; D. BOTTARO. - In: FEBS LETTERS. - ISSN 0014-5793. - STAMPA. - 250:(1989), pp. 469-473.

The 18 kDa cytosolic acid phosphatase from bovine liver has phosphotyrosine phosphatase activity on the auto phosphorylated epidermal grwth factor receptor

RAMPONI, GIAMPIETRO;MANAO, GIAMPAOLO;CAMICI, GUIDO;CAPPUGI, GIANNI;RUGGIERO, MARCO;
1989

Abstract

In this paper we demonstrate that the cytosolic low-Mr acid phosphatase purified from bovine liver has phosphotyrosine protein phosphatase activity on 32P-autophosphorylated epidermal growth factor (EGF) receptor. This activity was significantly inhibited by orthovanadate and p-hydroxymercuribenzoate; the latter result indicates that free sulfhydryl groups are required for phosphotyrosine phosphatase activity. The enzyme was active in a broad pH range, with maximum activity between pH 5.5 and 7.5. The apparent Km for 32P-EGF receptor dephosphorylation was 4 nM. The enzyme appeared to be specific for phosphotyrosine in that it dephosphorylated the autophosphorylated EGF receptor and L-phosphotyrosine, but not 32P-Ser-casein, L-phosphoserine or L-phosphothreonine. These data suggest that the cytosolic low-Mr acid phosphatase might play a regulatory role in EGF receptor-dependent transmembrane signalling.
1989
250
469
473
G. RAMPONI ; G. MANAO ; G. CAMICI ; G. CAPPUGI; M. RUGGIERO ; D. BOTTARO
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Utilizza questo identificatore per citare o creare un link a questa risorsa: https://hdl.handle.net/2158/205317
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