Proteolytic cleavage of Trop2 at Arg87 is mediated by matriptase and regulated by Val194
Pradnya R. Kamble, Sanjana Rane, Ananya A. Breed, Shaini Joseph, Smita D. Mahale, Bhakti R. Pathak
Abstract
Proteolytic processing is an important post‐translational modification affecting protein activity and stability. In the current study, we investigate the N‐terminal cleavage of Trop2, a protein which is overexpressed in many cancers. We demonstrate that Trop2 is cleaved at Arg87 by a transmembrane serine protease, matriptase. Homology modeling and site‐directed mutagenesis of amino acids in close proximity to the matriptase cleavage site reveal the importance of Val194 in regulating Trop2 cleavage. Co‐immunoprecipitation studies confirm that amino acid substitutions at Arg87, Thr88, Lys189, Val194, and His195 do not affect Trop2 dimerization. However, cleavage of wild‐type Trop2 by matriptase is inhibited when it is allowed to dimerize with a V 194 A mutant monomer, further confirming the role of Val194 in matriptase‐mediated N‐terminal cleavage.