A SNARE for fast endocytosis

Afusion-promoting exocytic protein is also required for fast endocytosis, based on results from Ferenc Deák, Thomas Südhof, Ege Kavalali (UTSW, Dallas, TX), and colleagues. The requirement may give hints about how neurons recycle synaptic vesicles back into the cell so rapidly, and how exocytosis prepares the way for such a fast process.

Exocytosis is greatly reduced but not eliminated at synapses lacking the SNARE fusion-promoting protein synaptobrevin/VAMP. The group found that endocytosis was delayed in these neurons even if amounts of exocytosis were first equalized at wild-type and mutant synapses by using different stimulation protocols. Dyes provided a further suggestion that mutant synapses had selectively lost fast endocytosis, as mutant synapses released both fast- and slow-diffusing styryl dyes and wild-type synapses released only the fast-diffusing dye.

Hints of an endocytic SNARE role have been seen previously in yeast...