Predominantly monomeric and to lesser extent homodimeric in endoplasmic reticulum, endoplasmic reticulum-Golgi intermediate compartment and cis-Golgi network. Oligomerizes with other members of the EMP24/GP25L family such as TMED2, TMED9 and TMED10. Interacts (via C-terminus) with COPG1; the interaction involves dimeric TMED7.