1.W.8. The (Enterobacterial phage T4) Portal Protein 8 (PPP8) Family
The phage T4 protein forms the portal vertex of the capsid (Michaud et al. 1989; Padilla-Sanchez et al. 2014). This portal plays critical roles in head assembly, genome packaging, neck/tail attachment, and genome ejection into the cytoplasm of the host cell. The portal protein multimerizes as a single ring-shaped homododecamer arranged around a central channel and binds to the terminase subunits to form the packaging machine. It attaches to the host inner membrane, most likely through interaction with the host YidC protein and forms together with chaperone gp40 an initiator complex to form the prohead Fokine et al. 2004; Quinten and Kuhn 2012).