Figure 8. ISO6 binds to RNA homopolymers.

Extracts from STEK Fmr1 ^−/− KO cells expressing ISO6 (A) and ISO7 (B) were mixed with agarose beads carrying polyA, polyU, polyC and polyG homopolymers. Captured proteins in the presence of 150 and 300 mM NaCl were eluted with SDS-sample buffer and analyzed by immunoblotting using mAb1C3. (C) Cleaved ISO6 in Cajal bodies also binds preferentially to polyG and to a lesser extend to polyU as is the case for ISO7 and ISO1 (not shown) FMRP.