| Feature | Current best-supported description | Evidence type (experimental vs inference) | Key sources (with year) |
|---|---|---|---|
| Protein identity/length | Gene 35 of *Enterobacteria phage T4* encodes long-tail fiber protein gp35, a monomeric “kneecap”/hinge component of the long tail fiber; gp35 is reported as a 372-residue polypeptide and ~30 kDa protein. | Experimental for identity/component assignment and mass; inference/review synthesis for exact descriptive role wording. | Hyman & van Raaij 2018; Leiman et al. 2010 (pqac-00000000, pqac-00000003) |
| Virion localization | gp35 localizes to the hinge (knee-cap) region at the junction between the phage-proximal half-fiber and phage-distal half-fiber of the long tail fiber (LTF). | Experimental (mass mapping/EM, stoichiometric tables) plus review synthesis. | Bartual et al. 2010; Leiman et al. 2010; Hyman & van Raaij 2018 (pqac-00000004, pqac-00000003, pqac-00000001) |
| Role in long tail fiber architecture | gp35 links the C-termini of trimeric gp34 to the N-termini of trimeric gp36, forming the bend between proximal and distal rods and helping create the fixed-angle architecture of the LTF. | Experimental for junction placement; inference/bioinformatic-structural interpretation for “fixed-angle bend” mechanism. | Hyman & van Raaij 2018; Bartual et al. 2010 (pqac-00000001, pqac-00000000, pqac-00000004) |
| Stoichiometry | The LTF has stoichiometry (gp34)3(gp35)1(gp36)3(gp37)3; gp35 is the only non-trimeric major structural component and occurs once per fiber. | Experimental/review compilation from structural and compositional studies. | Leiman et al. 2010; Bhatt et al. 2021; Mourosi et al. 2022 (pqac-00000003, pqac-00000007) |
| Assembly pathway placement | Assembly proceeds by formation of a gp36-gp37 complex, then gp35 joins the free end to form the distal half-fiber gp35-gp36-gp37; this distal half subsequently connects to proximal gp34. | Experimental/review synthesis from genetic, protein isolation, EM, and mass-mapping studies. | Hyman & van Raaij 2018 (pqac-00000002, pqac-00000001) |
| Predicted domain architecture (HHpred/CBM-like) | No experimental gp35 structure is available, but HHpred-based analysis predicts two carbohydrate-binding module-like domains: residues 19-178 similar to PDB 5GGN and residues 228-344 similar to CBM22 tandem-like fold (PDB 4XUP). These domains are proposed to mediate protein-protein contacts with gp34/gp36 rather than carbohydrate binding. | Inference/bioinformatic prediction. | Hyman & van Raaij 2018 (pqac-00000000) |
| Known structural data availability | Unlike gp34 and gp37, gp35 has no experimentally determined high-resolution structure reported in the provided evidence. | Experimental absence / review summary. | Hyman & van Raaij 2018; Bartual et al. 2010 (pqac-00000000, pqac-00000004) |
| Related proteins and receptor-binding context | gp34 forms the proximal trimeric rod; gp36 forms the upper/distal rod segment; gp37 forms the distal receptor-binding tip. The complete T4 LTF mediates initial reversible attachment to *E. coli* receptors including LPS and OmpC, but receptor recognition is attributed primarily to gp37 rather than gp35. | Experimental for gp37 receptor-binding context and LTF composition; review synthesis for division of roles. | Bartual et al. 2010; Mourosi et al. 2022; Granell et al. 2017 (pqac-00000004, pqac-00000007, pqac-00000006) |
| Key measurements | T4 LTFs are ~145 nm long and ~4 nm wide, often described as two ~80 nm rods joined end-to-end; scanning transmission microscopy resolved ~17 mass domains across the fiber, including a single gp35 hinge domain. T4 infection efficiency has been reported to approach the theoretical value of 1 in the context of efficient LTF-mediated host surface exploration. | Experimental for dimensions/domain mapping; review synthesis for infection-efficiency framing. | Granell et al. 2017; Hyman & van Raaij 2018; Mourosi et al. 2022 (pqac-00000006, pqac-00000002, pqac-00000007) |


*Table: This table summarizes the best-supported functional annotation for bacteriophage T4 gene 35 product gp35 (UniProt P03742), focusing on its identity, localization, architectural role, stoichiometry, assembly position, and structural knowledge. It is useful as a concise evidence-based reference for distinguishing experimentally supported facts from current bioinformatic inference.*