KDSR, also known as 3-ketodihydrosphingosine reductase, is a 332 amino acid multi-pass membrane protein that localizes to the endoplasmic reticulum (ER) and belongs to the short-chain dehydrogenases/reductases (SDR) family. KDSR is a secreted protein which is weakly expressed in hematopoietic tissue. Also this protein catalyzes the reduction of 3-ketodihydrosphingosine (KDS) to dihydrosphingosine (DHS).