FIGURE 7.

ProNGF expressed in E. coli activates the TrkA-MAPK pathway. PC12 cells were treated as described under “Experimental Procedures” with proNGFE expressed in bacteria or 2.5S NGF purified from mouse submandibular glands. A, representative Western blot showing proNGFE induces TrkA and MAPK phosphorylation, whereas total TrkA and MAPK remain unchanged. B, TrkA phosphorylation: R² = 0.8 and 0.9 for proNGFE and 2.5S NGF, respectively. C, MAPK activation: R² = 0.9 for both proNGFE and 2.5S NGF. Results were obtained from three independent experiments. Error bars represent mean ± S.E. D, Coomassie Blue staining for proNGFE before the assay. E, proNGFE was intact after the TrkA-MAPK activation assay.