Syntaxin 11 is associated with SNAP-23 on late endosomes and the trans-Golgi network

SNARE proteins are known to play a role in regulating intracellular protein transport between donor and target membranes. This docking and fusion proc ess involves the interaction of specific vesicle-SNAREs (e.g. VAMP) with sp ecific cognate target-SNAREs (e.g, syntaxin and SNAP-23), Using human SNAP- 23 as the bait in a yeast two-hybrid screen of a human B-lymphocyte cDNA li brary, we have identified the 287-amino-acid SNARE protein syntaxin 11, Lik e other syntaxin family members, syntaxin 11 binds to the SNARE proteins VA MP and SNAP-23 in vitro and also exists in a complex with SNAP-23 in transf ected HeLa cells and in native human B lymphocytes. Unlike other syntaxin f amily members, no obvious transmembrane domain is present in syntaxin 11. N evertheless, syntaxin 11 is predominantly membrane-associated and colocaliz es with the mannose 6-phosphate receptor on late endosomes and the trans-Go lgi network. These data suggest that syntaxin 11 is a SNARE that acts to re gulate protein transport between late endosomes and the trans-Golgi network in mammalian cells.