Beaded Filament Structural Protein 2 (BFSP2)

More than 99% of the vertebrate ocular lens consists of terminally differentiated lens fiber cells. Two lens-specific intermediate filament-like proteins, the protein product of this gene and filensin, are expressed only after fiber cell differentiation has begun. Both proteins are found in a structurally unique cytoskeletal element that is referred to as the beaded filament (BF). Mutations in this gene have been associated with juvenile-onset, progressive cataracts and Dowling-Meara epidermolysis bullosa simplex.Although CP49 did not fit unambiguously into any of the existing IF classes on the basis of sequence identity, the number (6) and locations of its introns are identical to those seen in type I cytokeratins. The authors corrected the bovine CP49 sequence and found that the human and bovine CP49 proteins are 89% identical.