Figure 3.

Immunoprecipitation/Westerns of TT-trk cells. TT cells expressing trkA, trkB, trkC, or an empty vector (neo) were serum starved then treated either with the appropriate ligand (+) or with media containing carrier alone (−). TT-trkA cells were treated with NGF, TT-trkC with NT-3, and TT-trkB with BDNF. The TT-neo cells were treated as indicated. After 10 min of treatment, the cells were harvested and the trk receptor proteins were immunoprecipitated by using a pan-trk antibody. The immunoprecipitated proteins were separated by SDS/PAGE and detected with either the pan-trk antibody or an antiphosphotyrosine antibody. No cell line showed increased tyrosine phosphorylation after incubation with the inappropriate ligand (for example, TT-trkA cells did not show increased phosphorylation after incubation with BDNF) (data not shown).