PEPTIDE MASS FINGERPRINTING OF CHAPERONIN-CONTAINING TCP-1 (CCT) AND COPURIFYING PROTEINS

The chaperonin-containing TCP-1 (CCT), found in the eukaryotic cytosol , is currently the focus of extensive research, CCT isolated from mous e testis lysate sediments at 20S in a sucrose gradient and accounts fo r about 70% of the total protein in this fraction. We intend to identi fy all the other proteins that copurify with CCT and to compile a refe rence profile for future studies. Their identification can be accelera ted by a combination of protease digestion, matrix-assisted laser deso rption-mass spectrometry, and database matching known as peptide mass fingerprinting, We applied this strategy to 32 polypeptides resolved b y 2-dimensional gel electrophoresis, and 23 known proteins and 6 novel proteins were identified, We analyzed isoelectric variants of the CCT subunits and differences in the peptide mass spectra of two CCT theta isoforms indicated a novel posttranslational modification of this sub unit.