 Wagner et al., suggest that chitin might have a microscopic function observed in cell to cell signaling and the manufacture of insect cuticle for example might represent a recurrent change in the location of expression chitin
Speculative, but however Chitin synthase is maintained in many lineages where it does not have an obvious macroscopic function.It is thought that because so many organisms share such a profound degree of genetic and molecular similarity that shifts in the location of expression might be a regular occurrence throughout time.Molecular analysis shows that proteins that seem to have a single specific function are instead found in many different tissue types.