Figure 4.

The packaging motor, P4: (A) The P4 X-ray crystal structure (PDB: 5MUV) fitted into the density of an asymmetric reconstruction of the five-fold vertex of the nucleocapsid (EMDB: 3573), surrounded by the P8 layer. (B) A section through the reconstruction at the contact plane reveals four possible connections (*), with the fifth (#) not quite forming a connection. (C) Side view showing the connections between P4 and the capsid shell below. (D) The C-terminal tail of P4 (blue) traverses the surfaces of P1_A (light blue) and P1_B (red) [48].