| Claim/annotation aspect | Key evidence (brief) | Source (author year journal) | Publication date | URL/DOI | Citation ID |
|---|---|---|---|---|---|
| Function | T4 gp29 is explicitly identified as the tail “tape measure”/elongated ruler protein that controls tail tube length; tail tube polymerization stops when gp29 is fully extended. | Arisaka et al. 2016 *Biophysical Reviews* | Nov 2016 | https://doi.org/10.1007/s12551-016-0230-x | (pqac-00000001) |
| Function | Review of T4 structure/function states gp29 is an “elongated ruler protein” and that the tail tube probably polymerizes along it, while noting the detailed incorporation mechanism remains unclear. | Yap & Rossmann 2014 *Future Microbiology* | Dec 2014 | https://doi.org/10.2217/fmb.14.91 | (pqac-00000006) |
| Localization | Table of T4 tail proteins places gp29 in the “Hub (tape measure),” i.e., the central baseplate hub region from which the tail grows. | Arisaka et al. 2016 *Biophysical Reviews* | Nov 2016 | https://doi.org/10.1007/s12551-016-0230-x | (pqac-00000007) |
| Localization | Biochemical and immunoprecipitation evidence indicates gp29 is present in baseplate fractions and becomes shielded as gp19 polymerizes around it, supporting localization in the central hub/tail channel during assembly. | Lou 2002 dissertation/thesis | 2002 | Not available from retrieved record | (pqac-00000005, pqac-00000002) |
| Role in assembly | Structural model of T4 baseplate/tail assembly concludes that gp54 together with gp29 initiates polymerization of gp19 to form the tail tube. | Yap et al. 2016 *PNAS* | Feb 2016 | https://doi.org/10.1073/pnas.1601654113 | (pqac-00000015, pqac-00000017) |
| Role in assembly | Earlier gene/protein analysis identified gp29 among the tube-associated proteins required for tail-tube assembly and central hub formation. | Ishimoto et al. 1988 *Virology* | May 1988 | https://doi.org/10.1016/0042-6822(88)90622-8 | (pqac-00000003) |
| Length determination mechanism | Proteolysis and assembly-intermediate analysis support a model in which one end of gp29 is buried in the baseplate hub while the other extends through the growing tail tube as an internal ruler; gp19 polymerizes around gp29 and occludes it. | Lou 2002 dissertation/thesis | 2002 | Not available from retrieved record | (pqac-00000000, pqac-00000002) |
| Length determination mechanism | Review summarizing T4 morphogenesis states tail tube polymerization stops when gp29 is fully extended, with gp3 binding contributing to termination of further polymerization. | Arisaka et al. 2016 *Biophysical Reviews* | Nov 2016 | https://doi.org/10.1007/s12551-016-0230-x | (pqac-00000001) |
| Stoichiometry/copy number | Central hub assembly was reported to involve six copies of gp29; later compiled structural summaries also list gp29 copy number as 6 and mass about 64.4 kDa. | Ishimoto et al. 1988 *Virology*; Gonzalez 2021 dissertation | May 1988; Aug 2021 | https://doi.org/10.1016/0042-6822(88)90622-8; https://doi.org/10.25394/pgs.15156780.v1 | (pqac-00000003, pqac-00000004) |
| Quantitative measurements | gp29 is 591 aa (~64,382 Da); if α-helical it would extend to ~91.7 nm, close to the measured T4 tail tube length of ~98.4 nm, supporting its ruler role. | Lou 2002 dissertation/thesis | 2002 | Not available from retrieved record | (pqac-00000000) |
| Quantitative measurements | T4 tail tube is described as built from 138 copies of gp19 in 23 hexameric rings in one review, whereas an older study cites 144 monomers of gp19 after initiation by gp54; assembled contractile tail length is ~98 nm. | Arisaka et al. 2016 *Biophysical Reviews*; Ishimoto et al. 1988 *Virology* | Nov 2016; May 1988 | https://doi.org/10.1007/s12551-016-0230-x; https://doi.org/10.1016/0042-6822(88)90622-8 | (pqac-00000001, pqac-00000003) |
| Current understanding from recent TMP research | Recent cryo-EM studies in other phages/injection systems show TMPs commonly form internal coiled-coil bundles, often trimers, can contact DNA, and are released or repositioned during infection—features consistent with the long internal-ruler model proposed for T4 gp29. | Ayala et al. 2023 *Nature Communications*; Cai et al. 2024 *Nature Communications*; Kizziah et al. 2024 *bioRxiv* | Dec 2023; Aug 2024; Dec 2024 | https://doi.org/10.1038/s41467-023-43824-9; https://doi.org/10.1038/s41467-024-51038-w; https://doi.org/10.1101/2024.12.10.627806 | (pqac-00000011, pqac-00000009, pqac-00000008) |


*Table: This table summarizes the main functional annotation claims for Enterobacteria phage T4 gp29 (UniProt P13337) and links each claim to the strongest available experimental or review evidence. It is useful for tracing how gp29 is annotated as a tape measure protein involved in tail assembly, localization, and tail length determination.*