Involved in transport of proteins from the cis/medial-Golgi to the trans-Golgi network. Part of a unique SNARE complex composed of the Golgi SNAREs GOSR1, STX5 and YKT6. Concentrated most in the intermediate compartment/cis-Golgi network and the cis-Golgi cisternae 1 and 2. Greatly reduced in concentration at the trans end of the Golgi apparatus. Belongs to the GOSR2 family.