Molecular fingerprinting of VNUT-containing compartments in Neuro-2a cells

Vesicular ATP release is involved in regulating biological processes like nociception, blood glucose, and vascular tone. ATP-containing vesicles are filled by the vesicular nucleotide transporter (VNUT) and are molecularly distinct from catecholaminergic vesicles of sympathetic neurons. This work sought to identify the molecular fingerprint of VNUT-containing vesicles. Fluorescence microscopy in Neuro-2a, HeLa, and HEK293 cells showed VNUT being widely dispersed throughout the cells with a perinuclear enrichment. VNUT failed to colocalize with known markers of synaptic vesicles, lysosomes, dense cored vesicles, and catecholaminergic vesicles. Bioinformatic analyses of mammalian VNUT C-terminus identified a unique KDEL-like HEDL motif, as well as a lack of classic synaptic vesicle-targeting dileucine-like and tyrosine-based motifs. This work suggests that VNUT likely resides primarily in the Golgi-ER complex, a previously unconsidered location for what is thought to be a vesicle-associated translocase.