Involved in the endoplasmic reticulum (ER) protein quality control and unfolded protein response. May be involved in the quality control of glycoproteins. Forms a complex in the ER with ERDJ3B and MED37A/BIP1 which is required for the proper accumulation and function of the surface-exposed leucine-rich repeat receptor kinases EFR involved in pathogen-associated molecular pattern (PAMP) triggered immunity. Interacts with ERDJ3B. By tunicamycin. No visible phenotype under normal growth conditions, but mutant plants are insensitive to seedling growth inhibition in response to the pathogen-associated molecular pattern (PAMP) elf18 and show increased susceptibility to phytopathogenic bacteria.