CYP1A-immunopositive proteins in bivalves identified as cytoskeletal and major vault proteins

To identify possible CYP1A-immunopositive proteins in bivalves, we used anti-fish CYP1A antibodies combined with one- and two-dimensional gel electrophoresis and mass spectrometry, and found that two of the main CYP1A-immunopositive proteins in digestive gland of Mytilus edulis, were cytoskeletal actin (42 kDa) and major vault protein (102 kDa), while the main CYP1A-immunopositive protein in the clam Chamaelea gallina was the cytoskeletal protein tropomyosin (33 kDa). Anti-CYP1A cross-reactive bands of 48–54 and 75 kDa in M. edulis were observed but not identified in this study. Sequence alignments with one of the most conserved CYP1A regions (NIRDITDSLIDHCED) from fish revealed similarities with tropomyosin and actin sequences from mussels, which could explain the immunological cross-reactivity. Changes in isoforms of tropomyosin after exposure to Aroclor1254 and Cu(II), could indicate modifications due to oxidative stress. Effects of pollutant related oxidative stress on the cytoskeleton require further studies.