All cytokeratin chains are composed of a central α-helix-rich domain (with a 50-90% sequence identity among cytokeratins of the same type and around 30% between cytokeratins of different type) with non-α-helical N- and C-terminal domains.
The end-domain sequences of type I and II cytokeratin chains contain in both sides of the rod domain the subdomains V1 and V2, which have variable size and sequence.