FIGURE 2.

CRM1 is a target of 15d-PGJ2. A, identified CRM1-peptides. Biotin-15d-PGJ₂-modified proteins from a HeLa-cell lysate were subjected to LC-ESI-MS/MS. The identity of peptide LLSEEVFDFSSGQITQVK was confirmed by sequencing (compare supplemental Fig. S1). The amino acids correspond to the human CRM1-sequence. B, a cell lysate was treated with (+) or without (−) biotinylated 15d-PGJ₂ and neutravidin-binding proteins (beads) were analyzed by Western blotting using an anti-CRM1 antibody. 1% of the supernatant (supe) was loaded. C, full mass spectrum of a CRM1 peptide modified by 15d-PGJ2. The peptide DLLGLCEQK (amino acids sequence 523–531 of CRM1) was treated with 15d-PGJ₂, and the samples were analyzed by mass spectrometry. The arrows show the peaks 667 and 1334, corresponding to the modified peptide doubly and singly charged, respectively. The arrowheads show the peaks corresponding to the unmodified peptides.