The Holin Hol44 (Hol44) Family (TC# 1.E.29) is a group of transporters belonging to the Holin Superfamily V. A representative list of proteins belonging to the Hol44 family from caudovirales and firmicutes can be found in the Transporter Classification Database.
One characteristic member of the Hol44 family is oenophage fOg44 (Lys44; TC# 1.E.29.2.1), which secretes an endolysin that Oenococcus oeni cells are intrinsically resistant to. Experiments with several antimicrobials support the hypothesis that the full activity of Lys44 requires sudden ion-nonspecific dissipation of the proton motive force, an event undertaken by the fOg44 holin in the phage infection context.
References
Hol44 family Wikipedia(Text) CC BY-SA