Critical regions for deubiquitinating activity of DUB-2 expressed in T-lymphocytes.

Ubiquitin- and proteasome-mediated protein degradation is involved in many intracellular processes, including cell cycle regulation, transcriptional activation, and signal transduction in all eukaryotes. Novel subfamily members of the ubp superfamily, DUB-1 and DUB-2, are known to be immediate-early genes and are specifically expressed in B-lymphocytes and T-lymphocytes, respectively. With the site-directed mutagenesis in four conserved amino acids (Cys60, Asp133, His298, and His307) and a series of deletion in the carboxy-terminal region, we demonstrate that these conserved amino acids are critical, but not the C-terminus, for the deubiquitinating activity of DUB-2.