| Autor: |
A D, Howard, M J, Kostura, N, Thornberry, G J, Ding, G, Limjuco, J, Weidner, J P, Salley, K A, Hogquist, D D, Chaplin, R A, Mumford |
| Rok vydání: |
1991 |
| Předmět: |
|
| Zdroj: |
Journal of immunology (Baltimore, Md. : 1950). 147(9) |
| ISSN: |
0022-1767 |
| Popis: |
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 (site 2). Cleavage at Asp116-Ala117 results in the generation of mature, biologically active IL-1 beta. ICE is unusual in that preferred cleavage at Asp-X bonds (where X is a small hydrophobic residue), has not been described for any other eukaryotic protease. To further examine the substrate specificity of ICE, proteins that contain Asp-X linkages including transferrin, actin, complement factor 9, the murine IL-1 beta precursor, and human and murine IL-1 alpha precursors, were assayed for cleavage by 500-fold purified ICE. The human and murine IL-1 beta precursors were the only proteins cleaved by ICE, demonstrating that ICE is an IL-1 beta convertase. Analysis of human IL-1 beta precursor mutants containing amino acid substitutions or deletions within each processing site demonstrated that omission or replacement of Asp at site 1 or site 2 prevented cleavage by ICE. To quantitatively assess the substrate requirements of ICE, a peptide-based cleavage assay was established using a 14-mer spanning site 2. Cleavage between Asp [P1] and Ala [P1']2 was demonstrated. Replacement of Asp with Ala, Glu, or Asn resulted in a greater than 100-fold reduction in cleavage activity. The rank order in position P1' was Gly greater than Ala much greater than Leu greater than Lys greater than Glu. Substitutions at P2'-P4' and P6' had relatively little effect on cleavage activity. These results show that ICE is a highly specific IL-1 beta convertase with absolute requirements for Asp in P1 and a small hydrophobic amino acid in P1'. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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