Analysis of organelle distribution and lysosomal protein composition of JIP3 KO axonal lysosomes. (A–C) JIP3 KO neurons triple stained for cathepsin B (A), AEP (B), and cathepsin D (C), along with both LAMP1 and MAP2. Arrows highlight representative axonal LAMP1 accumulations that have low levels of the respective lysosomal proteases compared with lysosomes of nearby neuronal cell bodies. (D and E) JIP3 KO neurons triple labeled for LAMP1 and MAP2 along with GM130 (D) or EEA1 (E), showing that axonal swellings filled with lysosomes (LAMP1 staining; arrows) are devoid of Golgi (D) and early endosomes (E). Images are representative of results from at least three independent JIP3 KO neuron cultures grown for 10–12 DIV. Bars, 10 µm.