| Aspect | Key findings | Evidence type | Primary citation (author, year, journal) | Publication date | URL/DOI |
|---|---|---|---|---|---|
| Identity | Target verified as bacteriophage T4 gene product 8 (gp8), a baseplate wedge structural protein in the T4 tail/baseplate system (pqac-00000010, pqac-00000008) | Primary study, review | Shneider et al., 2001, *Biochemistry (Moscow)* | Jun 2001 | https://doi.org/10.1023/A:1010271701204 |
| Role | gp8 is a core structural component of the baseplate wedge and contributes to baseplate organization near the center of the complex (pqac-00000012, pqac-00000002) | Cryo-EM, X-ray fit, review | Yap & Rossmann, 2014, *Future Microbiology* | Dec 2014 | https://doi.org/10.2217/fmb.14.91 |
| Interactions | gp8 binds a stretched 20-residue linker in gp7; gp7 residues 894-902 and 906-917 form beta-strand interactions with gp8 residues 323-334 from the two gp8 chains in the dimer (pqac-00000000) | Cryo-EM model with residue-level interface analysis | Yap et al., 2016, *PNAS* | Feb 2016 | https://doi.org/10.1073/pnas.1601654113 |
| Interactions | gp8 also participates in interwedge contacts; a 24-A loop in gp7 domain III (residues 454-475) is important for interwedge interactions with gp8 (pqac-00000003, pqac-00000011) | Cryo-EM reconstruction and fitted atomic models | Yap et al., 2016, *PNAS* | Feb 2016 | https://doi.org/10.1073/pnas.1601654113 |
| Assembly | Wedge assembly is ordered: gp7 monomer + gp10 trimer assemble first, followed by binding of a gp8 dimer, then a gp6 dimer (pqac-00000002, pqac-00000021) | Cryo-EM-informed assembly model, review | Yap et al., 2016, *PNAS* | Feb 2016 | https://doi.org/10.1073/pnas.1601654113 |
| Assembly | gp8 binding reduces gp7 flexibility and helps position gp7 so that gp6 can bind, completing wedge assembly (pqac-00000000) | Cryo-EM structural interpretation | Yap et al., 2016, *PNAS* | Feb 2016 | https://doi.org/10.1073/pnas.1601654113 |
| Assembly dependency | gp8 is required before gp6 can attach to the wedge and is reported as essential for gp6 folding (pqac-00000004) | Structural analysis, prior experimental interpretation | Aksyuk et al., 2009, *Structure* | Jun 2009 | https://doi.org/10.1016/j.str.2009.04.005 |
| Localization | gp8 localizes to the baseplate wedge of the virion; six wedges surround the central hub in the mature baseplate (pqac-00000008, pqac-00000020) | Review, cryo-EM context | Arisaka et al., 2016, *Biophysical Reviews* | Nov 2016 | https://doi.org/10.1007/s12551-016-0230-x |
| Stoichiometry | Tabled stoichiometry is 12 copies of gp8 per tail/baseplate, corresponding to 2 gp8 molecules per wedge across 6 wedges (pqac-00000008, pqac-00000020, pqac-00000022) | Review, cryo-EM, energetic modeling | Arisaka et al., 2016, *Biophysical Reviews* | Nov 2016 | https://doi.org/10.1007/s12551-016-0230-x |
| Structure | gp8 is a dimeric protein; in the wedge it is present as (gp8)2 and behaves as a relatively rigid structural element (pqac-00000000, pqac-00000012) | Cryo-EM, X-ray fit, review | Yap & Rossmann, 2014, *Future Microbiology* | Dec 2014 | https://doi.org/10.2217/fmb.14.91 |
| Structure | gp8 monomer architecture comprises two domains: domain I (residues 1-87 and 246-334) and domain II (residues 88-245); the dimer has a distinctive four-legged architecture (pqac-00000012) | X-ray structure summarized in review | Yap & Rossmann, 2014, *Future Microbiology* | Dec 2014 | https://doi.org/10.2217/fmb.14.91 |
| Quantitative biophysics | Recombinant gp8 is an alpha/beta protein with ~40% beta-structure and ~15% alpha-helix by CD spectroscopy (pqac-00000010, pqac-00000019) | CD spectroscopy | Shneider et al., 2001, *Biochemistry (Moscow)* | Jun 2001 | https://doi.org/10.1023/A:1010271701204 |
| Quantitative biophysics | Analytical ultracentrifugation gave gp8 sedimentation coefficient S20,w = 4.6S and showed dimeric and tetrameric species in solution (pqac-00000010, pqac-00000019) | Analytical ultracentrifugation | Shneider et al., 2001, *Biochemistry (Moscow)* | Jun 2001 | https://doi.org/10.1023/A:1010271701204 |
| Assembly intermediate data | Sedimentation of wedge intermediates increased from gp10-gp7 (10.2S) to gp10-gp7-gp8 (12.1S), consistent with gp8 incorporation into the growing wedge complex (pqac-00000023) | Analytical ultracentrifugation | Yap et al., 2010, *Macromolecular Bioscience* | Jul 2010 | https://doi.org/10.1002/mabi.201000042 |
| Conformational change | In the dome-shaped baseplate gp6 contacts gp8, but in the star-shaped activated baseplate gp6 no longer contacts gp8, indicating gp8-associated interfaces are remodeled during baseplate rearrangement (pqac-00000004) | Cryo-EM fitting and comparative structural analysis | Aksyuk et al., 2009, *Structure* | Jun 2009 | https://doi.org/10.1016/j.str.2009.04.005 |


*Table: This table summarizes experimentally supported functional annotation for bacteriophage T4 gp8 (UniProt P19062), including its role, interactions, assembly order, localization, stoichiometry, and quantitative biophysical properties. It is useful as a concise evidence map linking each annotation to specific primary literature and methods.*