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1.W.6.  The (Bacillus Phage phi29) Portal Protein 6 (PPP6) Family 

The phage phi29 portal protein forms the portal vertex of the capsid (Ibarra et al. 2000Fu and Prevelige 2009; Grimes et al. 2011). This portal plays critical roles in head assembly, genome packaging, neck/tail attachment, and genome ejection. The portal protein multimerizes as a single ring-shaped homododecamer arranged around a central channel (Guasch et al. 2002; Grimes et al. 2011). It binds to the 6 packaging RNA molecules (pRNA) forming a double-ring structure which in turn binds to the ATPase gp16 hexamer, forming the active DNA-translocating motor (Xiao et al. 2005; Simpson et al. 2000). This complex is essential for the specificity of packaging from the left DNA end. Thus, it is involved in viral genome ejection through the host cell envelope and penetration into the host cytoplasm.

References associated with 1.W.6 family:

Fu, C.Y. and P.E. Prevelige, Jr. (2009). In vitro incorporation of the phage Phi29 connector complex. Virology 394: 149-153. 19744688
Grimes, S., S. Ma, J. Gao, R. Atz, and P.J. Jardine. (2011). Role of φ29 connector channel loops in late-stage DNA packaging. J. Mol. Biol. 410: 50-59. 21570409
Guasch, A., J. Pous, B. Ibarra, F.X. Gomis-Rüth, J.M. Valpuesta, N. Sousa, J.L. Carrascosa, and M. Coll. (2002). Detailed architecture of a DNA translocating machine: the high-resolution structure of the bacteriophage φ29 connector particle. J. Mol. Biol. 315: 663-676. 11812138
Ibarra, B., J.R. Castón, O. Llorca, M. Valle, J.M. Valpuesta, and J.L. Carrascosa. (2000). Topology of the components of the DNA packaging machinery in the phage φ29 prohead. J. Mol. Biol. 298: 807-815. 10801350
Simpson, A.A., Y. Tao, P.G. Leiman, M.O. Badasso, Y. He, P.J. Jardine, N.H. Olson, M.C. Morais, S. Grimes, D.L. Anderson, T.S. Baker, and M.G. Rossmann. (2000). Structure of the bacteriophage φ29 DNA packaging motor. Nature 408: 745-750. 11130079
Xiao, F., W.D. Moll, S. Guo, and P. Guo. (2005). Binding of pRNA to the N-terminal 14 amino acids of connector protein of bacteriophage φ29. Nucleic Acids Res 33: 2640-2649. 15886394