| Claim/Topic | Key finding (1-2 sentences) | Evidence type | Source (first author, journal, year) | Publication date | URL/DOI | Notes/limitations |
|---|---|---|---|---|---|---|
| Enzymatic activity / substrate class | Human GK5 (UniProt Q6ZS86) is annotated as an FGGY-family glycerol kinase (EC 2.7.1.30), implying ATP-dependent phosphorylation of glycerol to glycerol-3-phosphate. In primary literature, recombinant GK5 showed glycerol kinase activity, supporting the annotation. (pqac-00000004, pqac-00000007) | UniProt-guided annotation supported by in vitro assay | Zhang, *PNAS*, 2017 | Jun 2017 | https://doi.org/10.1073/pnas.1705312114 | Direct activity evidence in retrieved text is largely from mouse/recombinant systems rather than purified human protein; substrate-specific kinetic constants were not available in retrieved evidence. |
| Subcellular localization | FLAG-tagged GK5-v2 localized mainly to the cytoplasm in transfected NIH 3T3 cells. The mechanistic work links GK5 to the SREBP processing pathway but does not establish stable ER/Golgi residency. (pqac-00000007) | Cell biology / imaging | Zhang, *PNAS*, 2017 | Jun 2017 | https://doi.org/10.1073/pnas.1705312114 | Localization evidence is from tagged protein in mouse fibroblasts, not endogenous human GK5. |
| Tissue specificity | GK5 was reported as predominantly expressed in sebaceous glands of skin, with skin-specific effects on lipid homeostasis; IHC showed strong sebaceous-gland staining in wild type and loss in mutant skin. (pqac-00000003, pqac-00000007, pqac-00000010) | Mouse genetics, histology, IHC | Zhang, *PNAS*, 2017 | Jun 2017 | https://doi.org/10.1073/pnas.1705312114 | Strong evidence for skin/sebocyte enrichment comes from mouse; direct human tissue-atlas quantitation was not retrieved. |
| Interaction partners | GK5 binds glycerol kinase (GK) via N-terminal FGGY_N domains and associates with SREBP-1 and SREBP-2 through their C-terminal regulatory domains. Binding to SREBPs appears kinase-independent, and purified GK5 did not phosphorylate immunoprecipitated SREBPs. (pqac-00000006) | Co-immunoprecipitation / domain mapping | Zhang, *PNAS*, 2017 | Jun 2017 | https://doi.org/10.1073/pnas.1705312114 | Human relevance is partially supported because endogenous associations were also observed in human HepG2 cells, but most mechanistic phenotyping was done in mouse systems. |
| Pathway role / biological process | GK5 acts as a negative regulator of SREBP-1/2 processing in skin. Loss of GK5 increased processed nuclear SREBPs and elevated SREBP target genes and lipids (cholesterol, triglycerides, ceramides), causing alopecia/hair-growth defects; simvastatin partially rescued the phenotype. (pqac-00000002, pqac-00000003, pqac-00000004) | Mouse genetics, immunoblotting, lipid phenotyping, pharmacologic rescue | Zhang, *PNAS*, 2017 | Jun 2017 | https://doi.org/10.1073/pnas.1705312114 | Best-supported function in retrieved literature is regulatory control of sterol/lipid biosynthesis in skin rather than classical housekeeping glycerol metabolism alone. |
| Disease / clinical relevance: EGFR-TKI resistance | In NSCLC, plasma exosomal GK5 mRNA was reported as significantly higher in gefitinib-resistant versus gefitinib-sensitive patients, and GK5 was upregulated in resistant PC9R/H1975 cells. GK5 silencing induced mitochondrial damage, caspase activation, cell-cycle arrest, and apoptosis via SREBP1/SCD1 signaling, suggesting biomarker and therapeutic-target potential. (pqac-00000005, pqac-00000014, pqac-00000015) | Clinical association, cell biology, functional knockdown | Zhou, *J Exp Clin Cancer Res*, 2019 | Feb 2019 | https://doi.org/10.1186/s13046-019-1057-7 | Retrieved excerpts did not include cohort size or effect-size statistics, so translational claims should be treated as promising but incompletely quantified here. |
| Recent cancer-context update | A 2024 ESCA study primarily analyzed GK, but specifically notes GK5 as one of three glycerol kinase variants and cites prior evidence that GK5 is elevated in gefitinib-resistant lung adenocarcinoma and promotes survival through SREBP1/SCD1. This serves as a recent secondary-source update rather than new GK5-specific mechanistic evidence in ESCA. (pqac-00000009, pqac-00000017) | Secondary discussion within a clinical association study | Ying, *Scientific Reports*, 2024 | Feb 2024 | https://doi.org/10.1038/s41598-024-54425-x | Important not to over-interpret: most quantitative results in this paper are for GK, not GK5. |
| Recent statistics from related glycerol-kinase cancer study | In ESCA, high GK expression was associated with worse overall survival and remained significant in multivariable analysis (univariate HR 1.289, 95% CI 1.004-1.655, p=0.046; multivariate HR 2.320, 95% CI 1.049-5.132, p=0.038). The same study reported 162 tumors vs 11 adjacent non-tumor samples and ~3% mutation frequency for GK. (pqac-00000008, pqac-00000018) | Clinical association / bioinformatics / IHC | Ying, *Scientific Reports*, 2024 | Feb 2024 | https://doi.org/10.1038/s41598-024-54425-x | These are GK statistics, included for context because the paper discusses GK5 only secondarily. |
| Review synthesis: skin/hair biology | Review literature cites GK5 dysfunction as causing the mouse *toku* phenotype with progressive hair loss and dermal lipid accumulation, placing GK5 within cholesterol/lipid homeostasis relevant to hair follicle biology and alopecia-related phenotypes. (pqac-00000000) | Review / expert synthesis | Palmer, *Experimental Dermatology*, 2020 | Mar 2020 | https://doi.org/10.1111/exd.13993 | Review-level evidence; not a primary source for mechanism beyond summarizing Zhang et al. |
| Review synthesis: sebaceous lipogenesis | A recent review on sebaceous lipogenesis highlights mouse sebaceous-gland expression of GK5 and its role in regulating cholesterol homeostasis/lipogenesis, reinforcing the view that GK5 is a specialized skin lipid regulator. (pqac-00000000) | Review / expert synthesis | Schmidt, *Communications Biology*, 2025 | Apr 2025 | https://doi.org/10.1038/s42003-025-08105-9 | Useful expert context, but outside the user's requested 2023-2024 priority window and largely derivative of earlier primary work. |
| Disease association database summary | Open Targets links human GK5 to ovarian neoplasm (score 0.3016), alopecia areata (0.2360), and neurodegenerative disease (0.4395), with evidence driven mainly by IMPC animal-model data and one CRISPR-screen pathway signal. (pqac-00000016) | Database association | Open Targets Platform entry for GK5 | 2025 platform citation | https://platform.opentargets.org/target/ENSG00000175066 | Association scores are hypothesis-generating, not proof of direct human causal function; mechanistic and clinical specificity for GK5 remains limited. |


*Table: This table compiles the strongest retrieved evidence about human GK5/Q6ZS86, including its inferred enzymatic role, experimentally supported skin/SREBP regulatory function, localization, and translational relevance. It is useful for separating direct primary evidence from review-level or database-level associations and for highlighting key limitations.*