PODXL long isoform with the H241R recoding event is more prone to protease digestion than other isoforms
(A) Western blot of trypsinized A549 cells overexpressing PODXL isoforms. Left: whole cell lysates. Right: cell lysates from the cell membrane fraction. The upper bands (∼180KD) represent intact PODXL proteins with posttranslational modifications. The middle and lower bands represent truncated PODXL proteins owing to trypsin digestion. See also Figure S2.
(B) Recoding RNA editing event H241R creates a novel trypsin digestion site on the PODXL long isoform. Top: Predicted trypsin cleavage sites on the edited PODXL long isoform. Bottom: Amino acid sequences around the H241R site with trypsin digestion sites labeled.
(C) Western blot of protease K treated A549 cells overexpressing PODXL isoforms. Whole cell lysates were used for Western blot. The upper bands (∼180KD) represent intact PODXL proteins with posttranslational modifications. The bands at 72KD ∼ 95KD have likely truncated PODXL proteins owing to protein degradation. The bands at ∼34KD are likely PODXL proteins lacking posttranslational modifications. The 10KD-to-26KD bands are digested PODXL proteins owing to protease K treatment.