Signal peptidase
The signal peptidase is an evolutionarily conserved membrane protease that cleaves the N-terminal signal peptide of secretory proteins. While prokaryotic signal peptidases function in a monomer, eukaryotic ones contain two non-catalytic subunits, Spc1 and Spc2.
Recently, we have found that transmembrane segments of membrane proteins become susceptible to cleavage by signal peptidase when Spc1 is deleted. When Spc1 was overexpressed, membrane protein processing was reduced, indicating that it regulates selection of membrane proteins for processing. Currently, we are investigating the roles of Spc1 and Spc2 in signal peptidase and their possible involvement in membrane protein biogenesis and degradation.