Predicted to enable signaling receptor binding activity. Involved in dorsal appendage formation; endoplasmic reticulum to Golgi vesicle-mediated transport; and regionalization. Located in endoplasmic reticulum membrane. Is expressed in adult head; adult heart; germarium; and nurse cell. Orthologous to several human genes including CNIH3 (cornichon family AMPA receptor auxiliary protein 3) and CNIH1 (cornichon family member 1).