The compact CERKL-mRNP complexes interact with microtubules.

HEK-293T cells were transfected with CERKL-WT and after 48 h a cytoskeletal fraction was isolated from the cells as described in Materials and Methods. Fractions were treated with 15 mM EDTA (A) or 100 µg/ml RNase A (B) in the presence of 150, 450 and 600 mM NaCl, as shown in the figure, and then subjected to immunoprecipitation with anti-Flag M2 affinity beads. The co-immunoprecipitated proteins were analyzed by immunoblot using antibodies that recognize eIF3B, PABP, HSP70, RPS3 and Flag (for CERKL). In the histograms below, the bands corresponding to the various proteins recovered after the Flag IP, in the presence of RNase A, were quantified with respect to CERKL-WT (A) or to CERKL-C125W (B) in each lane. Values are the mean from 4 different experiments. Stars indicate statistically significant differences from the values in the presence of 150 mM NaCl (*p<0.05, **p<0.01 and ***p<0.005).