Identification of TrkB autophosphorylation sites and evidence that phospholipase C-gamma 1 is a substrate of the TrkB receptor

J Biol Chem. 1994 Feb 18;269(7):5458-66.


The TrkB receptor protein-tyrosine kinase is a receptor for brain-derived neurotrophic factor and neurotrophin-3. In response to brain-derived neurotrophic factor and neurotrophin-3 treatment, TrkB expressed exogenously in Rat-2 cells is rapidly phosphorylated on tyrosine residues. At least 2 regions of TrkB contain phosphorylated tyrosines. The major sites of autophosphorylation are in the region containing Tyr-670, Tyr-674, and Tyr-675, which lies in the kinase domain and corresponds by sequence homology to the Tyr-416 autophosphorylation site in p60c-Src. Tyr-785, which lies just to the COOH-terminal side of the kinase domain in a relatively short tail characteristic of the Trk family of protein-tyrosine kinase receptors, is also phosphorylated in response to neurotrophin-3 treatment. The sequence around Tyr-785 fits a consensus sequence for binding phospholipase C-gamma 1. The simplest interpretation of these results is that, in response to neurotrophin binding, at least two and perhaps all three of the tyrosines in the Tyr-670/674/675 region are autophosphorylated independently, and Tyr-785 is autophosphorylated in vivo. Following activation of TrkB, phospholipase C-gamma 1 is phosphorylated on Tyr-783, Tyr-771, and Tyr-1254. Phospholipase C-gamma 1 also forms a complex with TrkB in response to neurotrophin-3 treatment, consistent with the possibility that one of the TrkB autophosphorylation sites provides a binding site for the phospholipase C-gamma 1 SH2 domains, as is the case for other receptor protein-tyrosine kinases. We conclude that phospholipase C-gamma 1 is directly phosphorylated by TrkB. Since phosphorylation of Tyr-783 and Tyr-1254 results in activation of phospholipase C-gamma 1, we predict that neurotrophin-3 leads to activation of phospholipase C-gamma 1 following binding to TrkB in Rat-2 cells.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Cell Line
  • Gene Expression / drug effects
  • Isoenzymes / metabolism*
  • Molecular Sequence Data
  • Nerve Growth Factors / pharmacology
  • Nerve Tissue Proteins / pharmacology
  • Neurotrophin 3
  • Peptide Fragments / chemistry
  • Peptide Fragments / isolation & purification
  • Peptide Mapping
  • Phosphopeptides / chemistry
  • Phosphopeptides / isolation & purification
  • Phosphorylation
  • Rats
  • Receptor Protein-Tyrosine Kinases / biosynthesis
  • Receptor Protein-Tyrosine Kinases / metabolism*
  • Receptor, trkB
  • Receptors, Nerve Growth Factor / biosynthesis
  • Receptors, Nerve Growth Factor / metabolism*
  • Substrate Specificity
  • Transfection
  • Trypsin
  • Type C Phospholipases / metabolism*


  • Isoenzymes
  • Nerve Growth Factors
  • Nerve Tissue Proteins
  • Neurotrophin 3
  • Peptide Fragments
  • Phosphopeptides
  • Receptors, Nerve Growth Factor
  • Receptor Protein-Tyrosine Kinases
  • Receptor, trkB
  • Type C Phospholipases
  • Trypsin