FIGURE 2.

The differential RET and TrkB surface levels depends on their intracellular portion. A, cell surface levels of RET and RET^TrkBIC receptors were compared. RET and RET^TrkBIC chimeric receptors were constructed on the pcDNA3.1 backbone and electroporated into PC12 cells. Surface proteins were collected by biotinylation methods and run on an SDS-PAGE gel. Cell lysates were added as protein level control. Immunoreactive bands were quantified by Image J software, and surface levels were represented as surface/lysate ratios. Relative receptor surface levels were normalized to that of RET. The results are represented as mean ± S.E. from three independent experiments (**, p < 0.01 versus RET surface levels; Student's t test). B, cell surface levels of TrkB^RETIC and TrkB receptors were compared. TrkB and TrkB^RETIC chimeric receptors were constructed on the pcDNA3.1 backbone and electroporated into PC12 cells. The same experiment process was carried out as in A. Relative receptor surface levels were normalized to that of TrkB^RETIC. The results are represented as mean ± S.E. from three independent experiments (**, p < 0.01 versus TrkB^RETIC surface levels; Student's t test).