Computer based sequence comparisons indicate partial sequence homology between human c-myc, Rous sarcoma virus, adenovirus 7, and simian sarcoma virus proteins and the cytoskeletal proteins desmin, keratin and vimentin. In addition, sections of the oncogene proteins showed partial but significant homology to α and β subunits of transducin, γ-II and β-BP crystallins showed partial but significant homology to the cytoskeletal proteins keratin, vimentin, desmin, α and β-tubulin, and to adenovirus 7 and simian sarcoma virus transforming gene proteins. β-BP crystallin showed partial but significant homology to Rous sarcoma virus protein, and to α and y subunits of transducin. Both crystallins showed partial sequence homology to the GTP-binding protein elongation factor TU from Escherichia coli. These sequence homologies suggest a link between the mechanisms of normal lens cell differentiation, involving modifications to the cytoskeleton and subsequent changes to the pattern of protein synthesis, and mechanisms of neoplastic transformation. Furthermore the transducin-like region on β-crystallin may be important for its interaction with lens membranes and the maintenance of short-range order for lens transparency.
