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Depolarization‐Dependent Tyrosine Phosphorylation in Rat Brain Synaptosomes
Author(s) -
Woodrow Sarah,
Bissoon Nankie,
Gurd James W.
Publication year - 1992
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1992.tb08323.x
Subject(s) - depolarization , synaptosome , phosphorylation , tyrosine , neuroscience , chemistry , biophysics , biology , biochemistry , central nervous system
Synaptosomes from rat forebrain were analyzed for the presence of phosphotyrosine‐containing proteins by immunoblotting with antiphosphotyrosine antibodies. Using this technique, 10–11 phosphotyrosine‐containing proteins were detected. Depolarization of synaptosomes by transfer to a high (41 mM ) K + medium resulted in increases in the phosphotyrosine content of several synaptosomal proteins, the most pronounced increase being associated with a membrane protein of M r 117,000 (ptp 117). Additional proteins exhibiting depolarization‐dependent increases in phosphotyrosine content had molecular weights of 39,000, 104,000, 135,000, and 160,000. The depolarization‐dependent increase in the phosphotyrosine content of ptp117 was apparent within 30 s of the onset of depolarization, reached a maximum between 3 and 5 min, and then decreased to near control values by 30 min. The increase in tyrosine phosphorylation of ptp117 was dependent on the concentration of K + in the depolarizing medium and was maximal with [K + ] in excess of 50 m M . It was also calcium dependent and did not occur in the absence of extracellular calcium. The addition of veratridine to the incubation medium also resulted in an increase in the tyrosine phosphorylation of ptpl 17. The results suggest that the phosphorylation of synaptic proteins on tyrosine residues may be involved in the regulation or modulation of synaptic activity.