Eukaryotic protein trafficking involves the packaging of target molecules into membranous vesicles that bud from a donor compartment, travel to a specific destination, fuse, and release their components into an acceptor compartment. Components of both the vesicle and the synaptic plasma membrane interact to form a fusion complex that mediates vesicle docking and fusion. This fusion complex contains NSF (N-ethyl-maleimide-sensitive factor), SNAPs (soluble NSF attachment proteins), and receptor proteins (SNAREs) that include synaptobrevin, synaptotagmin, syntaxin, and SNAP-25 (synaptosome-associated protein of 25 kDa). Interactions between vesicle SNAREs and target membrane SNARES mediates the specificity of docking. Along one pathway of protein trafficking, the Golgi apparatus receives proteins from the ER. These proteins move from cis-Golgi to trans-Golgi, through a stack of cisternae, towards the trans-Golgi network. From here, they are delivered to their proper destination in the cell. GS27 (Golgi SNARE of 27 kDa) (membrin) is a Golgi-associated SNARE. It functions in medial-to-trans-Golgi protein movement.