| Bioinformatics analyses and other observations of SIMPLE suggest that 1 ) it could be a member of the RING finger motif containing subfamily of E 3 ubiquitin ligases that are associated with the ubiquitin mediated proteasome processing pathway , 2 ) it could interact through its PPXY motifs with a WW domain containing protein , for instance with NEDD 4 , an E 3 ubiquitin ligase , and 3 ) it could interact through the PSAP motif with TSG 10 , a protein associated with endosomal multivesicular protein sorting . ^^^ Thus the potential E 3 ubiquitin ligase activity of SIMPLE , alteration in its interactions with NEDD 4 or TSG 101 , or changes in its properties as a clathrin coat adaptor may underlie the pathogenesis of Charcot Marie Tooth disease . . ^^^ |