A, The single intense band around 90 kDa is collected and trypsinized, and then sequenced by mass spectrometry. Blue amino acids were the sequences identified by mass spectrometry. B, 96-well plates were coated with HSP90β or BSA (100 µg/well). Coated plates were then incubated with serial concentrations of LAP proteins. The amount of binding LAP protein was determined by the anti-LAP antibody. Each value represents the mean of triplicate determinations; bars, SD. C, 293/EBNA and 293/EBNA-His-LAP cells were transiently transfected with HSP90β-HA. Supernatant was immunoprecipitated (IP) with the anti-His antibody (1st and 2nd rows) or anti-HA antibody (3rd lane), and then immunoblotted with anti-HA antibody (1st and 3rd rows) or anti-His antibody (2nd row).