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Neuronal protein tyrosine kinases associated with synaptosomal glycoproteins
Author(s) -
Hanissian S. H.,
Sahyoun N.
Publication year - 1992
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.490320413
Subject(s) - immunoprecipitation , proto oncogene tyrosine protein kinase src , glycoprotein , phosphorylation , tyrosine , tyrosine phosphorylation , tyrosine kinase , biology , receptor , membrane glycoproteins , biochemistry , microbiology and biotechnology , transmembrane protein , receptor tyrosine kinase , protein tyrosine phosphatase , gene
Protein tyrosine kinase (PTK) activity associated with synaptosomal membrane glycoprotein (SMGP) fractions of rat brain was examined. The synthetic substrate poly(Glu 4 ‐Tyr) was phosphorylated by SMGP in the presence of Mg 2+ and Mn 2+ , whose stimulatory effects were additive. In contrast, endogenous tyrosine phosphorylation in SMGPs was strictly dependent on Mn 2+ . Anti‐phosphotyrosine antibodies (PY20) immunoprecipitated two polypeptides in SMGPs of Mr 170K and 60K. Upon preincubation with IGF‐I, 97/90K polypeptides were phosphorylated, corresponding to the IGF‐I receptor beta‐subunits, and were immunoprecipitated with both PY20 and anti‐IGF‐I‐receptor antibodies. Immunoblot analysis using anti‐src antibody revealed that there was src protein associated with the glycoprotein fractions of solubilized synaptosomal membranes. Additional experiments revealed that the 60K tyrosine‐phosphorylated polypeptide present in the PY20 precipitates was indeed pp60 c‐src . This was confirmed by subjecting the PY20 immunoprecipitates to immunoblotting using anti‐src antibodies. In addition, src protein was directly immunoprecipitated by anti‐src antibodies from the SMGP preparations. Hence, IGF‐I receptors and glycoprotein‐associated PTKs in cluding pp60 c‐src may play an important role in synaptic transmembrane signalling, plasticity, and neuronal survival. © 1992 Wiley‐Liss, Inc.