Conformational defects underlie proteosomal degradation of Dent's disease-causing mutants of CLC-5

In this study we studied two misprocessed mutants: C221R located in the membrane domain and R718X, truncating the carboxy terminal domain. Both mutants exhibited enhanced protease susceptibility relative to the normal protein in limited proteolysis studies, providing direct evidence that they are misfolded. Interestingly, the membrane localized mutation: C221R, led to enhanced protease susceptibility of the cytosolic amino terminal region and the carboxy terminal truncation mutation: R718X led to enhanced protease susceptibility of both the cytosolic carboxyl and the membrane domains. Together, these studies support the idea that certain misprocessing mutations alter intramolecular interactions within the full length ClC-5 protein. Further, we found that these misfolded mutants are polyubiquitinated and targeted for proteosomal degradation in the OK renal epithelial cells, thereby ensuring that they do not elicit the unfolded protein response.

Source: BJ Cell - April 8, 2013 Category: Biochemistry Authors: C D'Antonio, S Molinski, S Ahmadi, L Huan, L Wellhauser, C E Bear Tags: BJ Disease Source Type: research