The lens-specific intermediate filament (IF) proteins CP49 and filensin have been identified in a large number of evolutionary divergent species. In the chick lens both CP49 and filensin have been identified. Recently a unique variant of CP49, CP49ins has been identified. CP49ins contains an insertion of 49 amino acids in helix 1 b giving it characteristics similar to the lamin-like cytoplasmic IF of invertebrates. The presence of this variant form in the chick lens poses some important questions about the co-assembly of the two CP49 forms and also the evolutionary relationship with invertebrate IF proteins.
- Cytoplasmic IF
- Intermediate filaments