The IFITM3 PPxY motif is required for ubiquitination by NEDD4.

<p>A-C) HEK293T cells were co-transfected with plasmids expressing myc-hIFITM3 or FLAG-NEDD4 as indicated. A-B) Cell lysates were immunoprecipitated with anti-myc resin, and examined by Western blotting with anti-myc and anti-ubiquitin (Ub). Western blotting of cell lysate with anti-FLAG antibodies was performed to confirm expression of NEDD4. Western blotting with anti-GAPDH antibodies was performed to confirm comparable protein loading. C) Cell lysates were immunoprecipitated with anti-myc or anti-FLAG resin, and co-immunoprecipitation was examined by Western blotting with both anti-myc and anti-FLAG antibodies for each immunoprecipitate. Western blots of cell lysates with anti-myc and anti-FLAG antibodies were performed to confirm expression of IFITM3 and NEDD4, respectively. Anti-GAPDH Western blotting was performed to confirm comparable protein loading.