Soluble N-ethylmaleimide sensitive factor attachment protein receptors (SNAREs) that reside in the target membranes and transport vesicles assemble into specific SNARE complexes to drive membrane fusion. N-ethylmaleimide sensitive factor (NSF) and its attachment protein, α-SNAP, catalyze disassembly of the SNARE complexes in the secretory and endocytic pathways to recycle them for the next round of the fusion event. γ-SNAP is an isoform of SNAP, but its function in SNARE-mediated membrane trafficking remains unknown. Here, we show that γ-SNAP regulates endosomal trafficking of epidermal growth factor receptor (EGFR) and transferrin. Immunoprecipitation and mass spectrometry revealed that γ-SNAP interacts with limited SNAREs including endosomal ones. γ-SNAP, as well as α-SNAP, mediated disassembly of endosomal syntaxin 7-containing SNARE complexes. Overexpression and small interfering RNA-mediated depletion of γ-SNAP changed the morphologies and intracellular distributions of endosomes. Moreover, the depletion partially suppressed the exit of EGFR and transferrin from EEA1-positive early endosomes to delay their degradation and uptake. Taken together, our findings suggest that γ-SNAP is a unique SNAP that functions in limited organelles including endosomes and their trafficking pathways.
- Received June 24, 2014.
- Accepted June 17, 2015.
- © 2015. Published by The Company of Biologists Ltd