Characterization of substrate specificity of the protein tyrosine phosphatase purified from the electric organ of Torpedo californica

Lin Mei, Kan Liao, Richard L. Huganir

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

The nicotinic receptor is highly phosphorylated on tyrosine residues both in vivo and in vitro. Tyrosine phosphorylation has been shown to regulate the functional properties of the receptor. We have purified a protein tyrosine phosphatase from the electric organ of Torpedo californica that dephosphorylates the nicotinic receptor. The unique biochemical properties of the purified enzyme suggest that it may be a novel phosphotyrosine protein phosphatase. In this report, substrate specificity of the protein purified from T. californica was characterized using four different tyrosine-phosphorylated substrate proteins. In addition to the nicotinic receptor, the Torpedo phosphatase dephosphorylated insulin receptor and Reduced Carboxamidomethylated and Meleylated lysozyme (RCM lysozyme), however, at a rate much slower than for the nicotinic receptor. In contrast, it appeared to have no effect on the phosphotyrosine level of pp15, a fatty acid binding protein (O-phospho-tyr19-422/aP2) phosphorylated by insulin receptor kinase in 3T3-L1 adipocytes. Interestingly, a protein tyrosine phosphatase (HA1) purified from adipocyte dephosphorylated both nicotinic receptor and pp15 at a similar rate. These results suggest that the Torpedo protein tyrosine phosphatase is relatively specific for the nicotinic receptor.

Original languageEnglish (US)
Pages (from-to)21-24
Number of pages4
JournalNeuroscience Letters
Volume182
Issue number1
DOIs
StatePublished - Nov 21 1994

Fingerprint

Electric Organ
Torpedo
Protein Tyrosine Phosphatases
Nicotinic Receptors
Substrate Specificity
Tyrosine
Insulin Receptor
Adipocytes
Fatty Acid-Binding Proteins
Phosphotyrosine
Phosphoprotein Phosphatases
Muramidase
Phosphoric Monoester Hydrolases
Proteins
Phosphotransferases
Phosphorylation
Enzymes

Keywords

  • Dephosphorylation
  • Insulin receptor
  • Ligand-gated ion channel
  • Lysozyme
  • Nicotinic acetylcholine receptor
  • pp15

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Characterization of substrate specificity of the protein tyrosine phosphatase purified from the electric organ of Torpedo californica. / Mei, Lin; Liao, Kan; Huganir, Richard L.

In: Neuroscience Letters, Vol. 182, No. 1, 21.11.1994, p. 21-24.

Research output: Contribution to journalArticle

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