A novel human protease similar to the interleukin-1β converting enzyme induces apoptosis in transfected cells

Abstract

We have identified a novel cDNA encoding a protein (named TX) with > 50% overall sequence identity with the interleukin-1β converting enzyme (ICE) and -30% sequence identity with the ICE homologs NEDD-2/ ICH-1(L) and CED-3. A computer homology model of TX was constructed based on the X-ray coordinates of the ICE crystal recently published. This model suggests that TX is a cysteine protease, with the pi aspartic acid substrate specificity retained. Transfection experiments demonstrate that TX is a protease which is able to cleave itself and the p30 ICE precursor, but not to generate mature IL-1β from pro-IL-1β. In addition, this protein induces apoptosis in transfected COS cells. TX therefore delineates a new member of the growing Ice/ced-3 gene family coding for proteases with cytokine processing activity or involved in programmed cell death.