Figure 29-2: Morphogenetic Pathway of P22. Approximately 420 molecules of the coat protein (gp5) co-assemble with approximately 300 molecules of the scaffolding protein (gp8). The minor (E) proteins, gp7, gp16, and gp20, as well as the portal protein (gp1) is incorporated during the early stages of assembly. The contameric dsDNA is delivered to the portal vertex by the action of a complex composed of gp2 and gp3 and packaged in a headful mechanism. Scaffolding exit is concomitant with packaging. Once a headful of DNA is packaged (~104% of the genome) the DNA is cut and the portal vertex stabilized by the addtion of gp4, gp10 and gp26. Up to six tailspike trimers (gp9) are now able to attach rendering the phage infectious.