Membrin also known as GOSR 2, GS 27 and GOS 27 is a 27 kDa membrane protein on the surface of the Golgi compartment. It has been shown to serve as a tSNARE in ER to Golgi transport.
In co-immunoprecipitation studies membrin was identified as a member of a SNARE complex consisting of syntaxin 5, GOSR 1 (GS 28, GOS 28), rbet1 and rsec22. A more detailed analysis revealed two subcomplexes within this complex. One contains syntaxin 5 (mainly the shorter 35 kDa variant) and GS 28 whereas the other is composed of syntaxin 5 (35 and 42 kDa variant), membrin, rsec22 and rbet1. It has been suggested that theses complexes mediate the fusion of ER-derived vesicles with vesicular tubular clusters (VTC), and the fusion of VTCs to form the cis-Golgi compartment.