IL-1-converting enzyme requires aspartic acid residues for processing of the IL-1 beta precursor at two distinct sites and does not cleave 31-kDa IL-1 alpha.

Abstract
IL-1 converting enzyme (ICE) specifically cleaves the human IL-1 beta precursor at two sequence-related sites: Asp27-Gly28 (site 1) and Asp116-Ala117