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. 2000 Mar 15;28(6):1365–1373. doi: 10.1093/nar/28.6.1365

Figure 4.

Figure 4

Photoaffinity labeling of purified Af-SRP54 with signal peptide. TDBA-modified lysine-tRNA was incorporated into the 86 amino acid residue bovine pre-prolactin (pPL) signal by translation in vitro (54) and used for photo cross-linking. The high-salt stripped nascent polypeptide–ribosome complex was mixed with either canine SRP54 or Af-SRP54 followed by centrifugation through a sucrose cushion. The radioactively labeled polypeptides were separated by SDS–PAGE on 12% gels and subjected to fluorography. Lane 1, non-irradiated pPL in the presence of canine SRP54; lane 2, irradiated pPL in the presence of canine SRP54; lane 3, non-irradiated pPL in the presence of recombinant Af-SRP54; lane 4, irradiated pPL in the presence of Af-SRP54. The arrowhead marks the position of Af-SRP54 cross-linked to the truncated (86 amino acid residues) pPL. Marker proteins with molecular weights in kDa are shown on the right.