Signal peptidase cleaves signal peptides of secretory proteins but it also processes membrane and viral proteins.  Although signal peptidase has been discovered more than three decades ago and highly conserved from bacteria to human, how it recognizes the substrate remains poorly defined. First project aims to elucidate the mechanisms of the signal peptidase mediated processing and maturation of secretory, membrane and viral proteins.

The majority of the mitochondrial proteins are encoded from nuclear genome and imported to the four different compartments in mitochondria (outer membrane, intermembrane space, inner membrane, and matrix). An increasing evidence shows that a large number of mitochondrial proteins is dually targeted, suggesting dynamic nature of mitochondrial protein targeting. How these complex and delicate targeting is accomplished in the cell remains an outstanding question. Second project aims to identify the signals for proper targeting of mitochondrial inner membrane proteins.