Role of vesicle-associated syntaxin 5 in the assembly of pre-Golgi intermediates.

Syntaxins are thought to function during vesicular transport as receptors on the target membrane and to contribute to the specificity of membrane docking and fusion by interacting with vesicle-associated receptors. Here, syntaxin 5 (Syn5) was shown to be an integral component of endoplasmic reticulum-derived transport vesicles. This pool, but not the target, Golgi-associated Syn5 pool, was essential for the assembly of vesicular-tubular pre-Golgi intermediates and the delivery of cargo to the Golgi. The requirement for vesicle-associated Syn5 in transport suggests a reevaluation of the basis for operation of the early secretory pathway.