Figure 7
FXR1P isoforms are associated with mRNPs present in polyribosomes. Aliquots containing ~12 A260 units of post-nuclear supernatants from non-induced myoblasts and from differentiated myotubes at day 3 were analyzed by sedimentation velocity through sucrose density gradients. Each collected fraction from gradients containing MgCl2 or EDTA (lower panels) was analyzed for the presence of all FXR1P isoforms using three different antibodies. Note that none of the antibodies used detect P82,84 in cytoplasmic extracts from myoblasts.