Fig. 3. CrkRS has an apparent M_r of 180 kDa on SDS-PAGE. (A) Affinity-purified anti-CrkRS antibodies are specific for CrkRS. Immunoblot of the GST-CrkRS C-terminal fragment (GST-CCT) fusion protein purified from E. coli and probed with affinity purified anti-CrkRS antibodies. The antibodies did not recognise the lane containing only GST (i), and pre-clearing the anti-CrkRS antiserum abolished the CrkRS signal (ii). (B) (His)₆-tagged human CRKRS expressed in Sf9 cells runs at 180 kDa. Anti-CrkRS immunoblot of lysates from Sf9 cells either uninfected, or infected with wild-type, or CrkRS-expressing baculovirus. (C) In vitro transcription/translation product of the CrkRS cDNA has an apparent M_r of 180 kDa. Full-length CrkRS was transcribed and translated in vitro from an expression vector containing the full length CrkRS cDNA (lane 2). An empty expression vector was used as a control (lane 1).