T4 structure - T4 Head
| Article Index |
|---|
| T4 structure |
| T4 Head |
| T4 Head - table |
| T4 Tail |
| T4 Tail - table |
| All Pages |
Gp Hoc (Highly Immunogenic Outer Capsid Protein, 39.1 kDa) is probably the most characteristic protein of the T4 capsid because of its regular location in the middle of each gp23 hexagon and because it protrudes considerably from the surface of the phage's head. This protrusion extends about 50 Ǻ over the capsid shell and it has a molecular weight of about 12 kDa. Hoc protein has a multidomain structure. It consists of a ~1.9-Ǻ-high round base, a thin neck region, and a ~20-Ǻ-wide and 24-Ǻ-high globular head. The function of gp Hoc is unknown (Leiman et al. 2003).
Fig 1. Protein structure of bacteriophage T4 head. A. General structure of bacteriophage T4 virion. B. Bacteriophage T4 head. Arrangement of proteins on head surface. Pentamers of gp24 are placed on head's corners while the rest of the surface is occupied by units made of gp23, gpsoc and gphoc. C. Reciprocal arrangement of head proteins. Hexamers of gp23 are surrounded by gpSoc except borders with gp24 pentamers. The middle of each hexamer occupies gpHoc.
