This family of proteins is found in viruses. Proteins in this family are approximately 60 amino acids in length. This family is a protein expressed by bacteriophages which has an unknown function. There is evidence that it is non-essential for in vivo production of a mature phage.

1: Gene K of bacteriophage phi X174 codes for a protein which affects the burst size of phage production. Gillam S, Atkinson T, Markham A, Smith M; J Virol. 1985;53:708-709. PMID:3155803