FIGURE 5.

Copurification of aminoacyl-tRNA synthetases with actin and with ribosomes. A, the polypeptides copurified with p38-CTAP were analyzed by SDS-PAGE and stained with Coomassie Blue (right) or silver nitrate (left). The identity of some of the low abundance polypeptides was determined by mass spectrometry. Polypeptides that could not be identified are marked with thin lines. B and C, protein complexes isolated using EF1Bβ-CTAP (B) or SerRS-CTAP (C) were analyzed as described above. The MARS complex purified from rabbit liver by conventional procedure (29) is indicated as a standard.