Sphingomyelin synthase-related protein 1 (Samd8)

Sphingomyelin synthases synthesize sphingolipids through transport of a phosphatidyl head set on to the primary hydroxyl of ceramide. SAMD8 is an endoplasmic reticulum (ER) transferase which has no sphingomyelin synthase activity but can convert phosphatidylethanolamine (PE) and ceramide to ceramide phosphatidylethanolamine (CPE) albeit with low product yield.

Appears to function as a ceramide detector to control ceramide homeostasis in the endoplasmic reticulum instead of a converter of ceramides. Appears to be critical for the integrity of the early secretory pathway (By similarity).