FIGURE 4.

Myo5a is absent from Myo5a^d-l/d-l synaptosomes as detected by Western blot analysis. A, comparison of major proteins present in rat wild type synaptosomes (Wt) and mouse dilute-lethal synaptosomes (Myo5a^d-l/d-l). Western blots revealed the presence of Rab3A, Rabphilin3A, and synaptophysin in both synaptosomal preparations, whereas Myo5a is absent in Myo5a^d-l/d-l synaptosomes. B, Western blots of bound proteins (BP) eluted from GST-Myo5a tail affinity columns probed for proteins as indicated. C, Rab3A from Myo5a^d-l/d-l-null mutant synaptosomes binds to Myo5a tail in a GTP-dependent manner. Inactivation of Rab3A in the presence of GDP resulted in binding of Rab3A (C, left panel) to RabGDI. Activation of Rab3A with GTP in the presence of GTPγS decreased binding affinity of Rab3A to RabGDI (C, right panel). Rabphilin3A could not be detected by Western blot analysis.