AHCYL1 (S-adenosylhomocysteine hydrolase-like 1), also known as DCAL, IRBIT or PRO0233, is an endoplasmic reticulum (ER) protein that is involved in amino acid biosynthesis. Expressed in dentritic blood cells (DCs), AHCYL1 functions to catalyze the H(2)O-dependent conversion of S-adenosyl-L-homocysteine to L-homocysteine and adenosine, a reaction that uses NAD as a cofactor. Additionally, AHCYL1 contains a PDZ-binding domain and a PEST region through which it can interact with IP3R-I (inositol 1,4,5-trisphosphate (IP3) receptor-I), a protein involved in various signaling pathways. This interaction lowers the affinity of IP3R-1 for its substrate, IP3, thereby decreasing the rate of IP3-IP3R-I binding. AHCYL1 shares 100% homology with its mouse counterpart, indicating a highly conserved function between species. Two isoforms of AHCYL1 are expressed due to alternative splicing events.