CSTF3 GI:75709187 cleavage stimulation factor subunit 3 isoform 2 1 msgdgateqa aeyvpekvkk aekkleenpy dldawsilir eaqnqpidka 50 51 rktyerlvaq fpssgrfwkl yieaevtilf yfflyqycsi hcsdrkqvrn 100 101 ian