SPPL2B is a member of the GXGD family of aspartic proteases. The GXGD proteases are transmembrane proteins with two conserved catalytic motifs localized within the membrane-spanning regions. This enzyme localizes to endosomes, lysosomes, and the plasma membrane. It cleaves the transmembrane domain of tumor necrosis factor alpha to release the intracellular domain, which triggers cytokine expression in the innate and adaptive immunity pathways.