| Functional role | Location in virion | Assembly order / interaction partners with stoichiometry | Structural / domain features | Quantitative data | Key experimental evidence incl. mutant phenotypes | Primary sources (year, DOI URL) |
|---|---|---|---|---|---|---|
| Major structural backbone of the T4 baseplate wedge; links proteins within a wedge, helps join wedges into the hexagonal baseplate, and transmits host-binding signals from the tail-fiber network to the inner baseplate to trigger sheath contraction and genome ejection during infection (pqac-00000000, pqac-00000001, pqac-00000002, pqac-00000006) | Distal tail/baseplate; distributed through the inner and intermediate regions of each wedge within the dome-shaped baseplate at the tail tip (pqac-00000000, pqac-00000001, pqac-00000004) | Ordered wedge assembly places gp7 early: gp10 then gp7, followed by gp8 and gp6, then gp53/gp25/gp11 depending on scheme reported; gp7 binds gp10 in the first step, forms a (gp10)3(gp7) hetero-tetramer, contacts gp8 and gp6, and participates in the (gp6)2-gp7 heterotrimer that helps join wedges; gp53 promotes association of six wedges into the baseplate; a gp10-gp7C18k-Hgp8 intermediate was reported with 3:1:2 stoichiometry; completed wedge stoichiometry reported as gp11:gp10:gp7:gp8:gp6:gp53:gp25 = 3:3:1:2:2:1:1 (pqac-00000005, pqac-00000006, pqac-00000007, pqac-00000002) | 1,032-residue elongated protein; described as six domains in Yap et al. and seven domains in Taylor et al.; flexible linkers connect domains; Domain III (residues 172-537) contains a ~24 Å loop (454-475) important for interwedge interactions with gp8; Domain VI (921-1001) interacts with the N-terminal region of gp10; residue 764 lies at the base of the conserved trifurcation unit; gp7 contains the only known inter-protein covalent bond in T4, linking gp7 to gp10; flexibility hindered crystallization (pqac-00000001, pqac-00000003, pqac-00000006) | One gp7 per wedge and six wedges per baseplate imply ~6 copies per mature baseplate; gp7 length 1,032 aa; intact in vitro assembled hubless baseplate-like particle ~3.3 MDa; cryo-EM structures reported at 3.8 Å for hubless baseplate/wedge model and 12 Å for earlier whole-baseplate reconstruction; baseplate dimensions in early cryo-EM ~520 Å diameter and ~270 Å long (pqac-00000000, pqac-00000002, pqac-00000004, pqac-00000006) | Cryo-EM and in vitro assembly showed gp7 is central to wedge architecture and star-shaped baseplate formation; protease-digestion experiments showed gp7 protects gp10 in complex formation; mutational analysis found d764 and i764 mutants insoluble, indicating structural importance of residue 764; particles carrying several gp7 mutants retained near-WT morphology by cryo-EM, suggesting assembly can still occur; infectivity assays showed d636/i636 and d846/i846 were near WT, while C184A reduced titer by ~20-fold, consistent with the functional importance of the gp7-gp10 covalent linkage for infection rather than gross assembly (pqac-00000003, pqac-00000007, pqac-00000000) | Yap et al., 2016, PNAS, https://doi.org/10.1073/pnas.1601654113; Taylor et al., 2016, Nature, https://doi.org/10.1038/nature17971; Arisaka et al., 2016, Biophysical Reviews, https://doi.org/10.1007/s12551-016-0230-x; Kostyuchenko et al., 2003, Nat Struct Biol, https://doi.org/10.1038/nsb970; Yap et al., 2010, J Mol Biol, https://doi.org/10.1016/j.jmb.2009.10.071 (pqac-00000000, pqac-00000001, pqac-00000002, pqac-00000004, pqac-00000005, pqac-00000006, pqac-00000007) |


*Table: This table condenses the best-supported structural and functional evidence for bacteriophage T4 gp7, including its role in wedge/baseplate assembly, infection triggering, virion localization, stoichiometry, and mutant phenotypes. It is useful as a quick-reference synthesis of the primary evidence directly relevant to UniProt P19061.*