Involved in the targeting and/or fusion of transport vesicles to their target membrane. Interacts with subunits of the vacuole protein sorting (HOPS) complex including VPS11, VCL1, VPS18, VPS33, VPS39 and VPS41. Strong colocalization with VAMP713 at the contact sites of two vacuoles. Highly expressed in stems and roots. Detected in flowers and leaves. The longin domain is critical for the vacuolar localization. Belongs to the synaptobrevin family.