AHCYL2 (also known as KIAA0828 or long-IRBIT) is highly homologous to IRBIT and interacts with and regulates NBCe1-B similar to IRBIT. The sequence of the N-terminus of AHCYL2 is highly similar to the N-terminus of IRBIT and contains protein phosphatase 1 (PP1)-binding site, PEST domain, C-C domain, and PDZ ligand. Besides, the N-terminus of AHCYL2 contains a long IRBIT-specific N-terminal (LISN) domain. However, unlike IRBIT, AHCYL2 only weakly interacts with IP3R. The protein encoded by AHCYL2 acts as a homotetramer and may be involved in the conversion of S-adenosyl-L-homocysteine to L-homocysteine and adenosine.