CSDE1 phosphorylation promotes interactions with the ribosome. (A) Co-IP of CSDE1 with ribosomal proteins in SK-Mel-147 lysates treated with phosphatase (PP) or with phosphatase in presence of inhibitors (PP + I). IgG was used as negative control. (NT) Not treated. (B) Quantification of RP coimmunoprecipitation. Values were corrected for CSDE1 IP efficiency and plotted relative to the levels in the PP + I condition (dashed line). Bar graphs represent the average of three independent experiments, and error bars indicate standard deviation. Significance was assessed by Student's t-test (*P ≤ 0.05, **P ≤ 0.01). (C) Model resulting from this work. CSDE1 isoform 2 (green) is expressed at low levels in normal melanocytes. Upon cell transformation, CSDE1 levels dramatically increase, concomitant with phosphorylation (yellow spheres), resulting in enhanced interactions with the ribosome and association to the ER (black arrows).
