This family consists of proteins of proteins belonging to the CpeT/CpcT family. These proteins are around 200 amino acids in length. The proteins contain a conserved motif PYR in the amino terminal half of the protein that may be functionally important. The species distribution of the family is interesting. So far it is restricted to cyanobacteria, cryptomonads and plants. It has been shown that CpcT encodes a bilin lyase responsible for attachment of phycocyanobilin to the beta subunit of phycocyanin.