?
Ubiquitin-specific protease 21 (Ubp21p) family, MATH domain; composed of fungal proteins with similarity to Ubp21p of fission yeast. Ubp21p is a deubiquitinating enzyme that may be involved in the regulation of the protein kinase Prp4p, which controls the formation of active spliceosomes. Members of this family are similar to human HAUSP (Herpesvirus-associated ubiquitin-specific protease) in that they contain an N-terminal MATH domain and a C-terminal catalytic protease (C19 family) domain. HAUSP is also an ubiquitin-specific protease that specifically catalyzes the deubiquitylation of p53 and MDM2. The MATH domain of HAUSP contains the binding site for p53 and MDM2. Similarly, the MATH domain of members in this family may be involved in substrate binding.