SYNJ1 and Parkinson disease: Several other endosomal proteins are involved in PD; DNAJC13, Putative tyrosine-protein phosphatase auxilin (DNAJC6), and the Rab protein GAK15 are involved in the uncoating of clathrin-coated vesicles [38,203,204], Ras-related protein Rab-7L1 has important roles in the retrograde trafficking of M6PRs to the Golgi apparatus [71,205,206], ATP6AP2 is essential for the biogenesis of active vacuolar H+-ATPase (V-ATPase) for the acidifications of LE and lysosomes [207], and SYNJ1 has an important role in endolysosomal trafficking of synaptic proteins [208,209].