Proximity labeling of dense core vesicle protein VMAT

Neuropeptide-containing dense core vesicles (DCVs) are generated in the neuronal cell body and circulate throughout the axonal arbor to supply distal release sites. This circulation depends on the anterograde kinesin-1 and kinesin-3 motors and the retrograde dynein-dynactin motor, however the adaptor proteins involved are poorly understood. In addition to their luminal neuropeptide cargo DCVs also contain specific transmembrane proteins including the vesicular monoamide transporter (VMAT). To identify potential components of DCV motor adaptor complexes in Drosophila neurons we performed proximity labeling based on a pan-neuronally expressed TurboID-VMAT chimera, as well as a free cytosolic TurboID used as a negative control. This approach may also shed light on the trafficking pathways involved in sorting VMAT and other membrane proteins to DCVs.