The low-affinity p75 nerve growth factor (NGF) receptor mediates NGF-induced tyrosine phosphorylation

Protein tyrosine phosphorylation is a potential mechanism for initial signaling in PC 12 cells during differentiation in response to nerve growth factor (NGF). NGF-induced tyrosine phosphorylation has been found to be initiated by the trk protooncogene, which participates in the formation of high-affinity NGF binding sites. In contrast to transfection of wild-type low-affinity p75 NGF receptors, transfection of p75^NGFR with mutations in the cytoplasmic domain resulted in an inability of NGF to elicit tyrosine phosphorylation of intracellular substrates, indicating that p75^NGFR is involved in initiating phosphorylation events by NGF. Even though the p75^NGFR receptor does not possess any inherent tyrosine kinase activity, these experiments demonstrate that the p75^NGFR has a potential role in NGF-induced tyrosine phosphorylation.