Fig. 6. Dyn3baa-induced filopodial outgrowth in mature neurons requires both the PRD of Dyn3 and full-length cortactin. (A) Dyn3aaa and Dyn3baa were truncated by 115 amino acids to remove the PRD and putative cortactin binding site. (B) Dyn3aaaPRD does not affect synaptogenesis. Neurons transfected with Dyn3aaaPRD-GFP show normal spine morphology at 18DIV. (C) Dyn3baaPRD does not induce filopodial outgrowth in mature neurons. Neurons transfected with Dyn3baaPRD-GFP exhibit normal spine morphology at 18DIV. (D) Cortactin was truncated by 73 amino acids, removing the SH3 domain and putative dynamin binding site. (E) Neurons co-transfected with Dyn3aaa and CortSH3-RFP display no morphological defects in mature spine development. (F) Dyn3baa requires full-length cortactin to cause filopodial outgrowth in mature neurons. Neurons co-transfected with Dyn3baa-GFP and CortSH3-RFP exhibit normal spine morphology at 18DIV, unlike neurons singly transfected with Dyn3baa-GFP. Scale bar, 5 µm.