The phage head-tail attachment protein is required for the joining of phage heads and tails at the last step of morphogenesis [1].

1: The solution structure of the bacteriophage lambda head-tail joining protein, gpFII. Maxwell KL, Yee AA, Arrowsmith CH, Gold M, Davidson AR; J Mol Biol 2002;318:1395-1404. PMID:12083526