Thymus Specific Serine Protease (TSSP)

TSSP is thought to play a role in the alternative antigen presenting pathway used by cortical thymic epithelial cells during the positive selection of T cells. The gene is found in the large histone gene cluster on chromosome 6, near the major histocompatibility complex (MHC) class I region. A second transcript variant has been described, but its full length nature has not been determined.The deduced 514-amino acid PRSS16 protein, which the authors termed TSSP, has a calculated molecular mass of 55 kD. PRSS16 contains a putative N-terminal signal peptide and a prolylendopeptidase consensus sequence. Within its 3-prime untranslated region, it has 2 different polyadenylation sites. PRSS16 shares sequence similarity with prolylcarboxypeptidase (PRCP), particularly around the active-site serine.