Required for normal Golgi morphology and function (By similarity). Ensures, when in complex with FPP3/VETH1 and FPP2/VETH2, the correct secondary cell wall (SCW) deposition pattern by recruiting exocyst components to cortical microtubules in xylem cells during secondary cell wall deposition (PubMed:25541219). Homodimer (PubMed:27448097). Component of the conserved oligomeric Golgi complex which is composed of eight different subunits and is required for normal Golgi morphology and localization (Probable). Binds to COG3 and COG4 (PubMed:27448097). Interacts with FPP3/VETH1 and FPP2/VETH2; this interaction promotes the association between cortical microtubules and EXO70A1 (PubMed:25541219). Binds to SEC15B, and, possibly, with EXO70A1, SEC3A and SEC10A (PubMed:27801942). Localized at vesicle-like small compartments at cortical microtubules. Belongs to the COG2 family.