The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.

We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.

Research report: Human GK5 (UniProt Q6ZS86) — functional annotation and biomedical relevance

0) Target verification (gene/protein identity)

The research target is human GK5 (UniProt Q6ZS86), described as glycerol kinase 5 (EC 2.7.1.30) and annotated to the FGGY kinase family (glycerol/hexitol kinase-like proteins). The retrieved primary literature explicitly uses “glycerol kinase 5 (GK5)” and provides functional and interaction evidence consistent with an FGGY-family glycerol kinase-like protein, supporting correct target alignment (zhang2017skinspecificregulationof pages 1-1, zhang2017skinspecificregulationof pages 7-8).

1) Key concepts and definitions (current understanding)

1.1 Canonical enzymatic role (definition)

Glycerol kinases catalyze ATP-dependent phosphorylation of glycerol to glycerol-3-phosphate (G3P), linking glycerol utilization to triglyceride/glycerophospholipid synthesis and broader intermediary metabolism. In the best mechanistic study available in this evidence set, recombinant GK5 demonstrated glycerol kinase activity in vitro (zhang2017skinspecificregulationof pages 3-3), consistent with its UniProt designation as an EC 2.7.1.30 enzyme.

Implication for substrate specificity: Within the retrieved corpus, GK5 is supported as a glycerol-directed phosphotransferase (glycerol → G3P), but no kinetic constants or systematic substrate-panel specificity (e.g., glycerol vs other polyols) were available in the retrieved excerpts (zhang2017skinspecificregulationof pages 3-3).

1.2 GK5 as a regulatory protein in lipid homeostasis (beyond “just” metabolism)

A major conceptual advance is that GK5 functions as a tissue-specialized regulator of SREBP activation in skin, not merely a housekeeping metabolic enzyme. In mouse skin, GK5 deficiency results in increased processing/activation of SREBP-1 and SREBP-2, accumulation of nuclear transcriptionally active SREBPs, and increased expression of multiple SREBP target genes involved in cholesterol and fatty-acid biosynthesis (e.g., Hmgcs1/2, Acaca, Fasn, Scd1, Ldlr, Fdps) (zhang2017skinspecificregulationof pages 6-7, zhang2017skinspecificregulationof pages 1-1).

Mechanistically, GK5 binds SREBP-1 and SREBP-2 via their C-terminal regulatory domains and inhibits their proteolytic processing/activation (zhang2017skinspecificregulationof pages 1-1, zhang2017skinspecificregulationof pages 7-8). This places GK5 functionally in the SREBP processing axis, a central lipid-sensing transcriptional program.

2) Cellular and tissue context (localization, expression, and where the protein acts)

2.1 Tissue specificity (skin/sebaceous gland enrichment)

The most direct expression evidence in the retrieved set indicates that GK5 is predominantly expressed in sebaceous glands of skin and is not detected in the corresponding GK5-deficient (“toku”) skin (zhang2017skinspecificregulationof pages 3-3). This is visually supported by immunohistochemistry showing sebaceous-gland GK5 staining in wild-type skin and loss of staining in mutant (zhang2017skinspecificregulationof media 30d0d1c2).

2.2 Subcellular localization

FLAG-tagged GK5 (isoform v2 in the cited work) localized mainly to the cytoplasm in transfected NIH 3T3 cells (zhang2017skinspecificregulationof pages 3-3). Functionally, GK5 is tied to the SREBP processing pathway (which involves ER/Golgi trafficking and regulated intramembrane proteolysis), but the retrieved evidence supports cytosolic localization for the tagged protein rather than definitive ER membrane residency (zhang2017skinspecificregulationof pages 7-8, zhang2017skinspecificregulationof pages 3-3).

3) Molecular mechanism and pathway placement

3.1 Interaction partners

GK5 physically associates with:
- GK (glycerol kinase; GK1/GK) via their N-terminal FGGY_N domains (zhang2017skinspecificregulationof pages 7-8).
- SREBP-1 and SREBP-2, binding to SREBP C-terminal regulatory domains (zhang2017skinspecificregulationof pages 7-8).

The binding to SREBPs is described as kinase-independent (binding does not require GK5 catalytic activity), and purified GK5 did not phosphorylate immunoprecipitated SREBP-1/2 under the tested conditions (zhang2017skinspecificregulationof pages 7-8). This supports a model where GK5 has dual attributes: enzymatic activity (glycerol kinase) plus non-catalytic scaffolding/regulatory interactions controlling SREBP processing.

3.2 Functional consequence: negative regulation of SREBP processing and lipid biosynthesis

In the skin-specific context, GK5 deficiency leads to elevated processed SREBPs and increased lipid biosynthesis, with downstream phenotypes including alopecia/hair-growth defects and accumulation of lipid species including cholesterol, triglycerides, and ceramides (zhang2017skinspecificregulationof pages 1-1). Pharmacologically, simvastatin partially rescued the phenotype, linking the pathology to sterol pathway overactivity (zhang2017skinspecificregulationof pages 1-1).

Visual support: the alopecia phenotype and sebaceous-gland GK5 expression are shown in figure crops (zhang2017skinspecificregulationof media 30d0d1c2). SREBP binding/co-immunoprecipitation and domain schematic evidence were also retrieved as figure crops from the same work (zhang2017skinspecificregulationof media 03a1d6d5, zhang2017skinspecificregulationof media aadb228b, zhang2017skinspecificregulationof media bd23a541).

4) Recent developments (prioritizing 2023–2024) and “latest research”

4.1 2024: Cancer-context synthesis mentioning GK5

A 2024 Scientific Reports study focused on glycerol kinase (GK) in esophageal carcinoma, but it includes GK5 in its biological background as one of three GK variants and cites prior evidence that GK5 is elevated in gefitinib-resistant lung adenocarcinoma and that GK5 silencing induces apoptosis through the SREBP1/SCD1 axis (ying2024glycerolkinaseenzyme pages 9-12).

Important scope note: this 2024 paper provides quantitative statistics for GK in ESCA (not GK5), so GK5-related content in that paper should be interpreted as secondary contextualization, not as new GK5-specific ESCA evidence (ying2024glycerolkinaseenzyme pages 5-7).

4.2 2023: Limited GK5-specific primary advances in retrieved set

Within the retrieved 2023–2024 corpus, GK5-specific primary mechanistic studies were sparse, and the strongest mechanistic basis remains the earlier high-quality PNAS study. A 2023 mitochondrial network expansion paper was retrieved but did not yield GK5-specific localization/function evidence from the excerpts examined (OpenTargets Search: -GK5).

5) Current applications and real-world implementations

5.1 Biomarker concept: exosomal GK5 mRNA for EGFR-TKI resistance

In NSCLC, exosomal GK5 mRNA detected in plasma was reported to be higher in patients with gefitinib-resistant adenocarcinoma than in gefitinib-sensitive cases, supporting a potential role as a liquid-biopsy biomarker candidate (zhou2019glycerolkinase5 pages 1-2). The same study used a tethered cationic lipoplex nanoparticle (TCLN) biochip for exosomal mRNA detection, reflecting a real-world oriented assay concept (zhou2019glycerolkinase5 pages 1-2).

5.2 Therapeutic hypothesis: targeting GK5 to reverse resistance

In gefitinib-resistant lung adenocarcinoma cell models, silencing GK5 induced mitochondrial damage, caspase activation, cell-cycle arrest, and apoptosis, implicating GK5 as a possible therapeutic target to overcome acquired resistance; mechanistically, the pathway is connected to SREBP1/SCD1 and intersects with EGFR signaling (zhou2019glycerolkinase5 pages 1-2, zhou2019glycerolkinase5 pages 11-12).

6) Expert opinions / authoritative synthesis

Reviews on hair/skin lipid biology explicitly highlight GK5 as a sebaceous-gland-associated factor where dysfunction causes the toku phenotype and lipid accumulation, situating GK5 as part of tissue lipid/cholesterol homeostasis relevant to hair disorders (OpenTargets Search: -GK5). These review statements largely synthesize the mechanistic primary work rather than introducing new experimental claims (OpenTargets Search: -GK5).

7) Relevant statistics and data (recent studies)

7.1 Quantitative data directly available in 2024 (note: GK, not GK5)

The 2024 ESCA study (GK-focused) provides quantitative clinical statistics that are informative for the broader glycerol-kinase/lipid-metabolism context:
- TCGA cohort comparison: 162 ESCA tumors vs 11 adjacent non-tumor samples, GK upregulated with p < 0.001 (ying2024glycerolkinaseenzyme pages 1-2).
- Survival/prognostic modeling: high GK expression associated with poorer OS; univariate HR 1.289 (95% CI 1.004–1.655), p=0.046 and multivariate HR 2.320 (95% CI 1.049–5.132), p=0.038 (ying2024glycerolkinaseenzyme pages 5-7).

These statistics do not quantify GK5, but they underscore the clinical relevance of glycerol-kinase–linked metabolic programs and motivate mechanistic work to distinguish GK versus GK2 versus GK5 roles (ying2024glycerolkinaseenzyme pages 9-12, ying2024glycerolkinaseenzyme pages 5-7).

7.2 OpenTargets quantitative association scores (hypothesis-generating)

Open Targets provides disease association scores for GK5, including:
- Neurodegenerative disease: 0.4395
- Ovarian neoplasm: 0.3016
- Alopecia areata: 0.2360
Evidence is driven largely by animal-model signals (IMPC) and a CRISPR-screen “affected pathway” signal in glutamatergic neurons (OpenTargets Search: -GK5).

8) Integrated functional model for human GK5 (Q6ZS86)

The best-supported functional annotation from the retrieved literature is that GK5 is a glycerol kinase-family protein with measurable glycerol kinase activity, but with a particularly important regulatory role in skin: GK5 associates with GK and binds SREBP-1/2 regulatory domains to suppress SREBP proteolytic activation, thereby restraining SREBP-driven lipid and sterol biosynthesis in sebaceous glands/skin (zhang2017skinspecificregulationof pages 6-7, zhang2017skinspecificregulationof pages 1-1, zhang2017skinspecificregulationof pages 7-8, zhang2017skinspecificregulationof pages 3-3). This specialization plausibly links GK5 to hair/skin lipid homeostasis phenotypes and connects it mechanistically to the SREBP axis, which is also implicated in cancer metabolic adaptation and therapy resistance (zhou2019glycerolkinase5 pages 1-2, zhou2019glycerolkinase5 pages 11-12).

9) Evidence map (summary table)

The following table compiles the strongest evidence, separating primary mechanistic results from review and database associations:

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.

10) Limitations and evidence gaps (important for functional annotation)

• Human-specific biochemistry: Within retrieved excerpts, the clearest enzymatic and mechanistic results come from mouse genetics and recombinant assays; there is limited direct biochemical characterization of purified human GK5 (e.g., Km for glycerol, substrate panel, regulation by metabolites) (zhang2017skinspecificregulationof pages 3-3).
• 2023–2024 GK5-specific primary literature scarcity: Recent papers retrieved either discuss GK5 secondarily or focus on related genes/proteins, limiting the ability to provide 2023–2024 GK5-specific mechanistic advances beyond cancer-context discussion (ying2024glycerolkinaseenzyme pages 9-12).
• Clinical quantitation for GK5 biomarker claims: The gefitinib-resistance study provides strong translational hypotheses but the retrieved excerpts did not include cohort size or effect sizes; full-text extraction would be needed for robust biomarker performance metrics (AUC, sensitivity/specificity) (zhou2019glycerolkinase5 pages 1-2).

Key sources (with URLs and publication dates where available)

• Zhang D. et al. PNAS (Jun 2017). “Skin-specific regulation of SREBP processing and lipid biosynthesis by glycerol kinase 5.” https://doi.org/10.1073/pnas.1705312114 (zhang2017skinspecificregulationof pages 1-1)
• Zhou J. et al. J Exp Clin Cancer Res (Feb 2019). “Glycerol kinase 5 confers gefitinib resistance through SREBP1/SCD1 signaling pathway.” https://doi.org/10.1186/s13046-019-1057-7 (zhou2019glycerolkinase5 pages 1-2)
• Ying F. et al. Scientific Reports (Feb 2024). “Glycerol kinase enzyme is a prognostic predictor in esophageal carcinoma and is associated with immune cell infiltration.” https://doi.org/10.1038/s41598-024-54425-x (ying2024glycerolkinaseenzyme pages 1-2)
• Open Targets Platform (platform citation: Buniello A. et al., Nucleic Acids Research, 2025). GK5 target page: https://platform.opentargets.org/target/ENSG00000175066 (OpenTargets Search: -GK5)

References

1. (zhang2017skinspecificregulationof pages 1-1): Duanwu Zhang, Wataru Tomisato, Lijing Su, Lei Sun, Jin Huk Choi, Zhao Zhang, Kuan-wen Wang, Xiaoming Zhan, Mihwa Choi, Xiaohong Li, Miao Tang, Jose M. Castro-Perez, Sara Hildebrand, Anne R. Murray, Eva Marie Y. Moresco, and Bruce Beutler. Skin-specific regulation of srebp processing and lipid biosynthesis by glycerol kinase 5. Proceedings of the National Academy of Sciences, 114:E5197-E5206, Jun 2017. URL: https://doi.org/10.1073/pnas.1705312114, doi:10.1073/pnas.1705312114. This article has 34 citations and is from a highest quality peer-reviewed journal.

2. (zhang2017skinspecificregulationof pages 7-8): Duanwu Zhang, Wataru Tomisato, Lijing Su, Lei Sun, Jin Huk Choi, Zhao Zhang, Kuan-wen Wang, Xiaoming Zhan, Mihwa Choi, Xiaohong Li, Miao Tang, Jose M. Castro-Perez, Sara Hildebrand, Anne R. Murray, Eva Marie Y. Moresco, and Bruce Beutler. Skin-specific regulation of srebp processing and lipid biosynthesis by glycerol kinase 5. Proceedings of the National Academy of Sciences, 114:E5197-E5206, Jun 2017. URL: https://doi.org/10.1073/pnas.1705312114, doi:10.1073/pnas.1705312114. This article has 34 citations and is from a highest quality peer-reviewed journal.

3. (zhang2017skinspecificregulationof pages 3-3): Duanwu Zhang, Wataru Tomisato, Lijing Su, Lei Sun, Jin Huk Choi, Zhao Zhang, Kuan-wen Wang, Xiaoming Zhan, Mihwa Choi, Xiaohong Li, Miao Tang, Jose M. Castro-Perez, Sara Hildebrand, Anne R. Murray, Eva Marie Y. Moresco, and Bruce Beutler. Skin-specific regulation of srebp processing and lipid biosynthesis by glycerol kinase 5. Proceedings of the National Academy of Sciences, 114:E5197-E5206, Jun 2017. URL: https://doi.org/10.1073/pnas.1705312114, doi:10.1073/pnas.1705312114. This article has 34 citations and is from a highest quality peer-reviewed journal.

4. (zhang2017skinspecificregulationof pages 6-7): Duanwu Zhang, Wataru Tomisato, Lijing Su, Lei Sun, Jin Huk Choi, Zhao Zhang, Kuan-wen Wang, Xiaoming Zhan, Mihwa Choi, Xiaohong Li, Miao Tang, Jose M. Castro-Perez, Sara Hildebrand, Anne R. Murray, Eva Marie Y. Moresco, and Bruce Beutler. Skin-specific regulation of srebp processing and lipid biosynthesis by glycerol kinase 5. Proceedings of the National Academy of Sciences, 114:E5197-E5206, Jun 2017. URL: https://doi.org/10.1073/pnas.1705312114, doi:10.1073/pnas.1705312114. This article has 34 citations and is from a highest quality peer-reviewed journal.

5. (zhang2017skinspecificregulationof media 30d0d1c2): Duanwu Zhang, Wataru Tomisato, Lijing Su, Lei Sun, Jin Huk Choi, Zhao Zhang, Kuan-wen Wang, Xiaoming Zhan, Mihwa Choi, Xiaohong Li, Miao Tang, Jose M. Castro-Perez, Sara Hildebrand, Anne R. Murray, Eva Marie Y. Moresco, and Bruce Beutler. Skin-specific regulation of srebp processing and lipid biosynthesis by glycerol kinase 5. Proceedings of the National Academy of Sciences, 114:E5197-E5206, Jun 2017. URL: https://doi.org/10.1073/pnas.1705312114, doi:10.1073/pnas.1705312114. This article has 34 citations and is from a highest quality peer-reviewed journal.

6. (zhang2017skinspecificregulationof media 03a1d6d5): Duanwu Zhang, Wataru Tomisato, Lijing Su, Lei Sun, Jin Huk Choi, Zhao Zhang, Kuan-wen Wang, Xiaoming Zhan, Mihwa Choi, Xiaohong Li, Miao Tang, Jose M. Castro-Perez, Sara Hildebrand, Anne R. Murray, Eva Marie Y. Moresco, and Bruce Beutler. Skin-specific regulation of srebp processing and lipid biosynthesis by glycerol kinase 5. Proceedings of the National Academy of Sciences, 114:E5197-E5206, Jun 2017. URL: https://doi.org/10.1073/pnas.1705312114, doi:10.1073/pnas.1705312114. This article has 34 citations and is from a highest quality peer-reviewed journal.

7. (zhang2017skinspecificregulationof media aadb228b): Duanwu Zhang, Wataru Tomisato, Lijing Su, Lei Sun, Jin Huk Choi, Zhao Zhang, Kuan-wen Wang, Xiaoming Zhan, Mihwa Choi, Xiaohong Li, Miao Tang, Jose M. Castro-Perez, Sara Hildebrand, Anne R. Murray, Eva Marie Y. Moresco, and Bruce Beutler. Skin-specific regulation of srebp processing and lipid biosynthesis by glycerol kinase 5. Proceedings of the National Academy of Sciences, 114:E5197-E5206, Jun 2017. URL: https://doi.org/10.1073/pnas.1705312114, doi:10.1073/pnas.1705312114. This article has 34 citations and is from a highest quality peer-reviewed journal.

8. (zhang2017skinspecificregulationof media bd23a541): Duanwu Zhang, Wataru Tomisato, Lijing Su, Lei Sun, Jin Huk Choi, Zhao Zhang, Kuan-wen Wang, Xiaoming Zhan, Mihwa Choi, Xiaohong Li, Miao Tang, Jose M. Castro-Perez, Sara Hildebrand, Anne R. Murray, Eva Marie Y. Moresco, and Bruce Beutler. Skin-specific regulation of srebp processing and lipid biosynthesis by glycerol kinase 5. Proceedings of the National Academy of Sciences, 114:E5197-E5206, Jun 2017. URL: https://doi.org/10.1073/pnas.1705312114, doi:10.1073/pnas.1705312114. This article has 34 citations and is from a highest quality peer-reviewed journal.

9. (ying2024glycerolkinaseenzyme pages 9-12): Fei Ying, Xuyong Chen, and Lihong Lv. Glycerol kinase enzyme is a prognostic predictor in esophageal carcinoma and is associated with immune cell infiltration. Scientific Reports, Feb 2024. URL: https://doi.org/10.1038/s41598-024-54425-x, doi:10.1038/s41598-024-54425-x. This article has 11 citations and is from a peer-reviewed journal.

10. (ying2024glycerolkinaseenzyme pages 5-7): Fei Ying, Xuyong Chen, and Lihong Lv. Glycerol kinase enzyme is a prognostic predictor in esophageal carcinoma and is associated with immune cell infiltration. Scientific Reports, Feb 2024. URL: https://doi.org/10.1038/s41598-024-54425-x, doi:10.1038/s41598-024-54425-x. This article has 11 citations and is from a peer-reviewed journal.

11. (OpenTargets Search: -GK5): Open Targets Query (-GK5, 5 results). Buniello, A. et al. (2025). Open Targets Platform: facilitating therapeutic hypotheses building in drug discovery. Nucleic Acids Research.

12. (zhou2019glycerolkinase5 pages 1-2): Jian Zhou, Guimei Qu, Ge Zhang, Zuoren Wu, Jing Liu, Dawei Yang, Jing Li, Meijia Chang, Hengshan Zeng, Jie Hu, Tao Fang, Yuanlin Song, and Chunxue Bai. Glycerol kinase 5 confers gefitinib resistance through srebp1/scd1 signaling pathway. Journal of Experimental & Clinical Cancer Research : CR, Feb 2019. URL: https://doi.org/10.1186/s13046-019-1057-7, doi:10.1186/s13046-019-1057-7. This article has 43 citations.

13. (zhou2019glycerolkinase5 pages 11-12): Jian Zhou, Guimei Qu, Ge Zhang, Zuoren Wu, Jing Liu, Dawei Yang, Jing Li, Meijia Chang, Hengshan Zeng, Jie Hu, Tao Fang, Yuanlin Song, and Chunxue Bai. Glycerol kinase 5 confers gefitinib resistance through srebp1/scd1 signaling pathway. Journal of Experimental & Clinical Cancer Research : CR, Feb 2019. URL: https://doi.org/10.1186/s13046-019-1057-7, doi:10.1186/s13046-019-1057-7. This article has 43 citations.

14. (ying2024glycerolkinaseenzyme pages 1-2): Fei Ying, Xuyong Chen, and Lihong Lv. Glycerol kinase enzyme is a prognostic predictor in esophageal carcinoma and is associated with immune cell infiltration. Scientific Reports, Feb 2024. URL: https://doi.org/10.1038/s41598-024-54425-x, doi:10.1038/s41598-024-54425-x. This article has 11 citations and is from a peer-reviewed journal.

15. (zhang2017skinspecificregulationof pages 8-8): Duanwu Zhang, Wataru Tomisato, Lijing Su, Lei Sun, Jin Huk Choi, Zhao Zhang, Kuan-wen Wang, Xiaoming Zhan, Mihwa Choi, Xiaohong Li, Miao Tang, Jose M. Castro-Perez, Sara Hildebrand, Anne R. Murray, Eva Marie Y. Moresco, and Bruce Beutler. Skin-specific regulation of srebp processing and lipid biosynthesis by glycerol kinase 5. Proceedings of the National Academy of Sciences, 114:E5197-E5206, Jun 2017. URL: https://doi.org/10.1073/pnas.1705312114, doi:10.1073/pnas.1705312114. This article has 34 citations and is from a highest quality peer-reviewed journal.

16. (zhou2019glycerolkinase5 pages 12-12): Jian Zhou, Guimei Qu, Ge Zhang, Zuoren Wu, Jing Liu, Dawei Yang, Jing Li, Meijia Chang, Hengshan Zeng, Jie Hu, Tao Fang, Yuanlin Song, and Chunxue Bai. Glycerol kinase 5 confers gefitinib resistance through srebp1/scd1 signaling pathway. Journal of Experimental & Clinical Cancer Research : CR, Feb 2019. URL: https://doi.org/10.1186/s13046-019-1057-7, doi:10.1186/s13046-019-1057-7. This article has 43 citations.

Artifacts

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Citations

1. zhang2017skinspecificregulationof pages 3-3
2. zhang2017skinspecificregulationof pages 7-8
3. zhang2017skinspecificregulationof pages 1-1
4. ying2024glycerolkinaseenzyme pages 9-12
5. ying2024glycerolkinaseenzyme pages 5-7
6. ying2024glycerolkinaseenzyme pages 1-2
7. zhang2017skinspecificregulationof pages 6-7
8. zhang2017skinspecificregulationof pages 8-8
9. https://doi.org/10.1073/pnas.1705312114
10. https://doi.org/10.1186/s13046-019-1057-7
11. https://doi.org/10.1038/s41598-024-54425-x
12. https://doi.org/10.1111/exd.13993
13. https://doi.org/10.1038/s42003-025-08105-9
14. https://platform.opentargets.org/target/ENSG00000175066
15. https://doi.org/10.1073/pnas.1705312114,
16. https://doi.org/10.1038/s41598-024-54425-x,
17. https://doi.org/10.1186/s13046-019-1057-7,

GK5 (Human Glycerol Kinase 5): Function, Processes, and Localization

Gene Overview and Family

GK5 (glycerol kinase 5) is a human gene encoding a putative glycerol kinase enzyme, identified by the UniProt accession Q6ZS86 (www.genecards.org). It is located on chromosome 3q23 (www.proteinatlas.org) and is one of several glycerol kinase paralogs in the human genome. The GK gene on Xp21 encodes the classical cytosolic glycerol kinase important in general metabolism, while GK5 appears to be a tissue-specialized isozyme. Another paralog, GK2, is a retrogene expressed in testes (notably in the sperm tail) (www.genecards.org), highlighting how duplication created tissue-specific glycerol kinases. GK5 was originally annotated as a "putative" enzyme based on sequence homology (classified in the FGGY carbohydrate kinase family) (www.abcam.com). Its predicted molecular weight is ~60 kDa, and alternative splicing yields at least two transcript variants, though a 528–amino acid isoform (GK5-v2) is predominantly expressed in human tissues (pmc.ncbi.nlm.nih.gov). Initial bioinformatic analyses suggested GK5 might localize to mitochondria (www.ncbi.nlm.nih.gov), but subsequent experimental evidence refined our understanding of its cellular location and function, as detailed below.

Enzymatic Function and Substrate Specificity

GK5 is an enzyme that catalyzes the ATP-dependent phosphorylation of glycerol to produce sn-glycerol-3-phosphate (www.abcam.com). This reaction is the first and only step of the glycerol utilization pathway (polyol pathway) leading from free glycerol to glycerol-3-phosphate (www.abcam.com). Like the canonical glycerol kinase (EC 2.7.1.30), GK5 binds ATP and glycerol in its active site, transferring a phosphate group to glycerol (www.abcam.com). Biochemical studies have confirmed that GK5 indeed possesses glycerol kinase activity: recombinant human GK5 protein, when expressed and purified, can phosphorylate glycerol in vitro, with measurable enzymatic activity in the pmol/min·µg range (pmc.ncbi.nlm.nih.gov). Mutagenesis experiments identified two conserved aspartate residues (Asp-280 and Asp-443) critical for catalysis, as substitution of these residues abrogates GK5’s activity (pmc.ncbi.nlm.nih.gov). These residues are conserved in the FGGY kinase family and likely coordinate substrate or cofactor binding, indicating GK5 shares the catalytic mechanism of other glycerol kinases. Importantly, GK5 shows a high substrate specificity for glycerol – its physiological role is to channel glycerol into glycerol-3-phosphate, a key intermediate in lipid metabolism. Consistent with this function, UniProt and pathway databases place GK5 in the glycerol degradation and glycerol-3-phosphate biosynthesis pathways (www.abcam.com). In summary, GK5’s primary biochemical role is as a glycerol 3-phosphotransferase, generating glycerol-3-phosphate for downstream metabolic processes.

Role in Skin Lipid Metabolism and SREBP Regulation

One of the most striking aspects of GK5 is its specialized role in skin lipid homeostasis. Unlike the ubiquitously expressed X-linked GK enzyme, GK5 functions predominantly in the skin and notably in sebaceous glands (pmc.ncbi.nlm.nih.gov). A seminal 2017 study by Zhang et al. discovered GK5 as a previously unrecognized regulator of lipid synthesis in the skin (pmc.ncbi.nlm.nih.gov). In normal skin, GK5 acts as a negative regulator of SREBP signaling – it forms a complex with sterol regulatory element-binding proteins (SREBPs) (specifically binding the C-terminal regulatory domain of SREBP-1 and -2) and thereby inhibits SREBP processing and activation (pmc.ncbi.nlm.nih.gov). SREBPs are transcription factors that, when activated, translocate to the nucleus and upregulate nearly all enzymes required for cholesterol and fatty acid synthesis. By restraining SREBP activation in sebocytes, GK5 helps limit the expression of lipid biosynthetic genes in the skin (pmc.ncbi.nlm.nih.gov). In other words, GK5 serves as a “brake” on sebum lipid production under normal conditions, acting in a skin-specific feedback mechanism for cholesterol and fatty acid homeostasis (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). This regulatory function is independent of systemic cholesterol regulation in other tissues, making GK5 part of a skin-exclusive metabolic control system (pmc.ncbi.nlm.nih.gov).

The importance of GK5’s role was demonstrated by the Gk5^toku mouse model, a recessive loss-of-function mutant identified in an N-ethyl-N-nitrosourea (ENU) screen (pmc.ncbi.nlm.nih.gov). Mice lacking GK5 in the skin exhibited excessive accumulation of lipids – including cholesterol, triglycerides, and ceramides – in the skin, indicating that SREBP-driven lipid synthesis went unchecked without GK5 (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). These GK5-deficient mice developed pronounced alopecia (hair loss) due to impaired hair growth and maintenance (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Proper hair follicle function requires a balanced production of sebum lipids, and the GK5-null mice showed that too much cholesterol and other lipids in the skin can disrupt hair growth (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Mechanistically, in GK5-null (toku/toku) mice, the absence of GK5 led to uninhibited SREBP processing: the cleaved, active forms of SREBP-1 and SREBP-2 accumulated in the nucleus of skin sebocytes (while SREBP regulation in the liver remained normal) (pmc.ncbi.nlm.nih.gov). This resulted in overexpression of lipid-synthesis enzymes in the skin and overproduction of lipids. Notably, the phenotype could be partially reversed by treating the mice with simvastatin (an HMG-CoA reductase inhibitor that lowers cholesterol synthesis), which mitigated the excess cholesterol in skin and improved hair growth (pmc.ncbi.nlm.nih.gov). This rescue experiment provided strong evidence that the hair loss and skin abnormalities were indeed due to dysregulated cholesterol biosynthesis downstream of SREBP, linking GK5’s regulatory role to a physiological outcome (pmc.ncbi.nlm.nih.gov).

Intriguingly, the kinase activity of GK5 appears essential for its regulatory function in vivo. Mice engineered to express a kinase-dead GK5 mutant (with catalytic aspartates mutated) displayed similar hair growth defects as the null mutants (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). In these mice, GK5 protein was present but enzymatically inactive, and it failed to properly suppress SREBP-driven lipid synthesis, leading to the same pathological outcome. This finding suggests that it is not only the physical presence of GK5 but also its glycerol-phosphorylating activity that is required to control SREBP. One hypothesis is that the product of the GK5 reaction, glycerol-3-phosphate, or the act of ATP consumption might be integral to the signaling mechanism that restrains SREBP processing in sebaceous cells. Supporting the importance of GK5’s enzyme activity, researchers observed a compensatory upregulation of the X-linked glycerol kinase (GK) in the skin of GK5-knockout mice – enough to normalize total glycerol kinase activity in skin tissue (pmc.ncbi.nlm.nih.gov). Despite this compensation in glycerol phosphorylation capacity, the mice still showed lipid over-accumulation and hair loss, underscoring that GK5’s unique role in SREBP regulation could not be fulfilled by the other kinase (pmc.ncbi.nlm.nih.gov). Interestingly, GK5 and the canonical GK were found to physically interact in cells (pmc.ncbi.nlm.nih.gov), hinting at a possible hetero-oligomeric or complex formation. While the significance of GK5–GK interaction is not fully elucidated, it suggests coordination between the isozyme and the house-keeping enzyme, potentially to fine-tune glycerol metabolism or signaling in tissues where both are present (like skin). In summary, GK5’s primary biological role is twofold: (1) metabolic, providing glycerol-3-phosphate for lipid synthesis in sebaceous glands, and (2) regulatory, modulating the SREBP pathway to prevent excessive lipid production in the skin (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov).

Expression Patterns and Subcellular Localization

Tissue expression: GK5 is expressed in a broad range of tissues at the mRNA level, but with notably higher functional expression in skin. Transcriptomic surveys (e.g. GTEx and HPA) indicate GK5 mRNA is detected in virtually all examined tissues (low tissue specificity), with particularly appreciable levels in digestive tract, skin, and other organs (www.proteinatlas.org). Despite this widespread transcription, actual protein expression or abundance appears more restricted. In mice, Gk5 mRNA was found in many tissues, yet immunoblotting could detect GK5 protein only in the skin (and not in liver, muscle, adipose, brain, etc.) under normal conditions (pmc.ncbi.nlm.nih.gov). This suggests that GK5 protein expression is either very low or regulated post-transcriptionally outside of skin. In human protein profiling data, GK5 shows predominantly cytoplasmic immunoreactivity in many tissues, but the antibody staining intensity varies and is only moderately consistent with RNA levels (www.proteinatlas.org). The highest and most consistent expression of GK5 is observed in the skin’s sebaceous glands. Immunohistochemistry in mouse skin localizes GK5 strongly to sebaceous gland cells adjacent to hair follicles (pmc.ncbi.nlm.nih.gov), aligning with its role in sebum lipid metabolism. Therefore, GK5 can be considered a sebocyte-enriched enzyme, even though its gene is not truly tissue-exclusive (low-level expression elsewhere may not translate into significant protein function).

Subcellular localization: Bioinformatics initially predicted a mitochondrial localization for GK5 (possibly due to an N-terminal sequence resembling a mitochondrial targeting signal in one isoform) (www.ncbi.nlm.nih.gov). However, experimental evidence indicates that GK5 is primarily a cytosolic protein. When GK5 was expressed in cultured cells (e.g. FLAG-tagged human GK5 in NIH 3T3 fibroblasts), it was observed to reside mainly in the cytoplasm (pmc.ncbi.nlm.nih.gov). No specific accumulation in mitochondria was noted in these assays, and the protein lacked transmembrane regions, suggesting it is a soluble cytosolic enzyme. The UniProt/Swiss-Prot annotation, updated after functional studies, lists GK5 as an intracellular, cytosolic protein (www.abcam.com). Additionally, GK5’s interaction with SREBPs likely occurs at the cytosolic side of the endoplasmic reticulum or Golgi membranes where SREBP precursors are located. This implies that GK5 may associate with membranes or protein complexes in the cytosol without being an integral membrane protein. Consistently, the Human Protein Atlas reports “cytoplasmic and membranous expression in most tissues” for GK5 protein (www.proteinatlas.org), meaning GK5 can sometimes be seen in a punctate pattern near membranes (possibly reflecting proximity to ER or lipid droplets in sebocytes). Overall, GK5 carries out its function in the cell interior, predominantly in the cytosolic compartment. Its cytosolic localization is appropriate for an enzyme that must access glycerol (a freely diffusible metabolite) and ATP, and that interacts with cytosolic domains of SREBP cleavage-regulating machinery.

Emerging Links to Disease and Current Research Insights

Beyond its fundamental role in skin biology, recent research has implicated GK5 in pathological and clinical contexts, highlighting its broader significance. One notable finding is the involvement of GK5 in cancer cell metabolism and drug resistance. Zhou *et al. (2019) discovered that GK5 is upregulated in certain therapy-resistant cancers, specifically in non-small cell lung cancer (NSCLC) cells resistant to the EGFR inhibitor gefitinib (pmc.ncbi.nlm.nih.gov). They found that GK5 mRNA and protein levels were significantly higher in gefitinib-resistant NSCLC cell lines (PC9/R and H1975) compared to their sensitive counterparts, and intriguingly, GK5 mRNA was also elevated in exosomes from the plasma of resistant patients (pmc.ncbi.nlm.nih.gov). This suggests GK5 might serve as a biomarker of drug resistance, potentially measurable via liquid biopsy. Functionally, GK5 appears to contribute to the resistance phenotype: knocking down GK5 in resistant lung cancer cells led to mitochondrial dysfunction, cell-cycle arrest, and apoptosis in those cells (pmc.ncbi.nlm.nih.gov). Mechanistic analysis linked this effect to the SREBP1/SCD1 lipid signaling pathway – silencing GK5 resulted in lower levels of active SREBP1 and its target stearoyl-CoA desaturase-1 (SCD1), a key enzyme in fatty-acid metabolism (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). The authors concluded that GK5 helps maintain SREBP1 activity and unsaturated lipid production in cancer cells, thereby promoting cell survival under drug treatment (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). In essence, a high GK5 level supports augmented lipogenesis (through SREBP/SCD1) which cancer cells can exploit to build membranes and combat the stress of EGFR inhibition. By preventing apoptosis in this way, GK5 confers a survival advantage – a phenomenon succinctly summarized by Zhou et al.: “GK5 confers gefitinib resistance in lung cancer by inhibiting apoptosis and cell cycle arrest” (pmc.ncbi.nlm.nih.gov). This finding is significant because it extends GK5’s relevance from a specialized metabolic enzyme in normal skin to a potential therapeutic target in oncology. If compounds could be developed to inhibit GK5, they might induce lipogenic collapse in tumor cells and restore sensitivity to treatments like tyrosine kinase inhibitors. Indeed, GK5 was proposed as a novel target for overcoming EGFR-inhibitor resistance in NSCLC (pmc.ncbi.nlm.nih.gov), though such strategies remain to be tested clinically.

The unique phenotype of GK5-deficient mice (alopecia with sebaceous lipid overload) also raises medical questions in dermatology. While no human hereditary disorder has yet been directly attributed to GK5 mutations, the mouse data suggest that variation in GK5 activity could impact skin and hair health. It is conceivable that polymorphisms or dysregulation of GK5 might contribute to conditions of sebaceous gland dysfunction – for example, disorders of hair growth, seborrhea, or acne – where lipid production is imbalanced. A 2019 molecular evolution study noted that certain sebum-producing genes are lost or inactivated in species that lack sebaceous glands (like whales) (academic.oup.com). Although GK5 itself was not highlighted in that study’s gene set, its role in sebocyte lipid regulation aligns with the concept of specialized lipid metabolism genes underpinning sebaceous gland function. Clinically, GK5 is beginning to appear in genetic testing panels and research. The NIH Genetic Testing Registry lists GK5 among genes of interest (updated in 2025) (www.cloud-clone.com), possibly in the context of multi-gene panels for skin disorders or metabolic studies. Further research is needed to determine if human GK5 variants cause subtle skin phenotypes or if GK5 expression changes are involved in common skin conditions. On the other hand, the cancer research community has taken interest in GK5 as illustrated by the NSCLC study and other metabolic works. GK5’s connection to the SREBP pathway ties it into a larger trend of investigating metabolic enzymes that double as regulatory proteins (sometimes termed “moonlighting” functions). For example, the liver-expressed glycerol kinase (GK) was recently shown to drive lipogenesis in fatty liver disease by activating SREBP-1c transcription (pmc.ncbi.nlm.nih.gov) (pubmed.ncbi.nlm.nih.gov), drawing a parallel to how GK5 modulates SREBP in skin. Such findings reinforce the idea that glycerol kinases are not mere passive metabolic catalysts but can actively influence lipid signaling networks.

Conclusion

GK5 (glycerol kinase 5) emerges as a multifaceted gene whose product plays a crucial role at the interface of metabolism and regulation in human cells. Biochemically, it performs a classic enzymatic function – phosphorylating glycerol to form glycerol-3-phosphate – thereby feeding into triglyceride synthesis and energy metabolism (www.abcam.com). Biologically, GK5 has carved out a niche in the skin, where it is predominantly expressed in sebaceous glands and acts as a watchdog of lipid production. It binds and restrains SREBP transcription factors in these cells, preventing overproduction of cholesterol and fatty acids in the skin (pmc.ncbi.nlm.nih.gov). This skin-specific function is vital for maintaining healthy hair and skin lipid balance, as evidenced by the alopecia and lipid accumulation seen in GK5-null mice (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). The enzymatic activity of GK5 is integral to this regulatory role, highlighting an elegant coupling between metabolism (glycerol-phosphate production) and signaling (SREBP modulation) in sebocytes (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Current research has expanded the relevance of GK5, identifying it as a player in cancer cell lipid metabolism and a potential mediator of drug resistance via the SREBP/SCD1 pathway (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). These insights underscore the broader principle that metabolic enzymes can have tissue-specific signaling functions with physiological and pathological consequences. Going forward, GK5 is a gene of interest in fields ranging from dermatology to oncology. Its study exemplifies how understanding the precise function, location, and interactions of a gene product can illuminate its role in health and disease. In summary, human GK5 is a glycerol kinase that not only fuels lipid synthesis with glycerol-3-phosphate, but also ensures that lipid synthesis in the skin is kept in check – a dual role that is supported by rigorous experimental evidence from molecular, cellular, and organismal studies (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov).

References: Key data and conclusions are drawn from recent authoritative sources, including Zhang et al. (2017) in PNAS (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov), which first elucidated GK5’s skin-specific function, and Zhou et al. (2019) in J. Exp. Clin. Cancer Res. (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov), which explored GK5 in cancer metabolism, among other database and literature resources as cited throughout. All evidence has been referenced with direct citations to ensure accuracy and provide original publication context (with publication dates and links for verification).

Citations

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19. AnnotationURLCitation(end_index=6771, start_index=6600, title='Skin-specific regulation of SREBP processing and lipid biosynthesis by glycerol kinase 5 - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5495269/#:~:text=We%20discovered%20a%20previously%20unrecognized,other%20skin%20lipids%20are%20necessary')
20. AnnotationURLCitation(end_index=7080, start_index=6941, title='Skin-specific regulation of SREBP processing and lipid biosynthesis by glycerol kinase 5 - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5495269/#:~:text=The%20recessive%20N,nucleus%20and%20led%20to%20elevated')
21. AnnotationURLCitation(end_index=7470, start_index=7299, title='Skin-specific regulation of SREBP processing and lipid biosynthesis by glycerol kinase 5 - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5495269/#:~:text=We%20discovered%20a%20previously%20unrecognized,other%20skin%20lipids%20are%20necessary')
22. AnnotationURLCitation(end_index=7610, start_index=7471, title='Skin-specific regulation of SREBP processing and lipid biosynthesis by glycerol kinase 5 - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5495269/#:~:text=The%20recessive%20N,nucleus%20and%20led%20to%20elevated')
23. AnnotationURLCitation(end_index=7889, start_index=7723, title='Skin-specific regulation of SREBP processing and lipid biosynthesis by glycerol kinase 5 - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5495269/#:~:text=of%20cholesterol%20regulation%20in%20other,other%20skin%20lipids%20are%20necessary')
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26. AnnotationURLCitation(end_index=8523, start_index=8384, title='Skin-specific regulation of SREBP processing and lipid biosynthesis by glycerol kinase 5 - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5495269/#:~:text=The%20recessive%20N,nucleus%20and%20led%20to%20elevated')
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31. AnnotationURLCitation(end_index=10401, start_index=10245, title='Skin-specific regulation of SREBP processing and lipid biosynthesis by glycerol kinase 5 - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5495269/#:~:text=but%20not%20in%20the%20liver%3B,regulation%20elsewhere%20in%20the%20body')
32. AnnotationURLCitation(end_index=11325, start_index=11174, title='Skin-specific regulation of SREBP processing and lipid biosynthesis by glycerol kinase 5 - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5495269/#:~:text=match%20at%20L681%20lipid%20synthesis,to%20bind%20to%20each%20other')
33. AnnotationURLCitation(end_index=11706, start_index=11555, title='Skin-specific regulation of SREBP processing and lipid biosynthesis by glycerol kinase 5 - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5495269/#:~:text=match%20at%20L681%20lipid%20synthesis,to%20bind%20to%20each%20other')
34. AnnotationURLCitation(end_index=11922, start_index=11791, title='Skin-specific regulation of SREBP processing and lipid biosynthesis by glycerol kinase 5 - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5495269/#:~:text=lipid%20synthesis,to%20bind%20to%20each%20other')
35. AnnotationURLCitation(end_index=12655, start_index=12484, title='Skin-specific regulation of SREBP processing and lipid biosynthesis by glycerol kinase 5 - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5495269/#:~:text=We%20discovered%20a%20previously%20unrecognized,other%20skin%20lipids%20are%20necessary')
36. AnnotationURLCitation(end_index=12800, start_index=12656, title='Skin-specific regulation of SREBP processing and lipid biosynthesis by glycerol kinase 5 - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5495269/#:~:text=expressed%20predominantly%20in%20sebaceous%20glands,specific')
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38. AnnotationURLCitation(end_index=13813, start_index=13700, title='Skin-specific regulation of SREBP processing and lipid biosynthesis by glycerol kinase 5 - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5495269/#:~:text=homozygote%20skin%20%28Fig,2D')
39. AnnotationURLCitation(end_index=14286, start_index=14125, title='Tissue expression of GK5 - Summary - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000175066-GK5/tissue#:~:text=Tissue%20distribution%20%28RNA%29,i%7D%20Image%3A%20Approved%20Approved')
40. AnnotationURLCitation(end_index=14609, start_index=14496, title='Skin-specific regulation of SREBP processing and lipid biosynthesis by glycerol kinase 5 - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5495269/#:~:text=homozygote%20skin%20%28Fig,2D')
41. AnnotationURLCitation(end_index=15225, start_index=15066, title='GK5 glycerol kinase 5 [Homo sapiens (human)] - Gene - NCBI', type='url_citation', url='https://www.ncbi.nlm.nih.gov/gene/256356#:~:text=Summary%20Predicted%20to%20enable%20glycerol,of%20Genome%20Resources%2C%20Jul%202025')
42. AnnotationURLCitation(end_index=15582, start_index=15463, title='Skin-specific regulation of SREBP processing and lipid biosynthesis by glycerol kinase 5 - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5495269/#:~:text=but%20not%20in%20other%20tissues,2D')
43. AnnotationURLCitation(end_index=15957, start_index=15861, title='GK5 | Abcam', type='url_citation', url='https://www.abcam.com/en-us/targets/gk5/23412#:~:text=Cellular%20localization')
44. AnnotationURLCitation(end_index=16562, start_index=16376, title='Tissue expression of GK5 - Summary - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000175066-GK5/tissue#:~:text=Tissue%20distribution%20%28RNA%29,IMMUNOHISTOCHEMISTRY%20DATA%20RELIABILITY%20Data%20reliability')
45. AnnotationURLCitation(end_index=17696, start_index=17524, title='Glycerol kinase 5 confers gefitinib resistance through SREBP1/SCD1 signaling pathway - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6385389/#:~:text=We%20found%20that%20the%20exosomal,apoptosis%20via%20SREBP1%2FSCD1%20signaling%20pathway')
46. AnnotationURLCitation(end_index=18139, start_index=17967, title='Glycerol kinase 5 confers gefitinib resistance through SREBP1/SCD1 signaling pathway - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6385389/#:~:text=We%20found%20that%20the%20exosomal,apoptosis%20via%20SREBP1%2FSCD1%20signaling%20pathway')
47. AnnotationURLCitation(end_index=18638, start_index=18456, title='Glycerol kinase 5 confers gefitinib resistance through SREBP1/SCD1 signaling pathway - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6385389/#:~:text=significantly%20upregulated%20in%20gefitinib,apoptosis%20via%20SREBP1%2FSCD1%20signaling%20pathway')
48. AnnotationURLCitation(end_index=19029, start_index=18872, title='Glycerol kinase 5 confers gefitinib resistance through SREBP1/SCD1 signaling pathway - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6385389/#:~:text=match%20at%20L507%20significantly%20repressed,2%20were%20also%20repressed')
49. AnnotationURLCitation(end_index=19202, start_index=19030, title='Glycerol kinase 5 confers gefitinib resistance through SREBP1/SCD1 signaling pathway - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6385389/#:~:text=match%20at%20L621%20inhibit%20the,resistance%20via%20SREBP1%2FSCD1%20signaling%20pathway')
50. AnnotationURLCitation(end_index=19541, start_index=19369, title='Glycerol kinase 5 confers gefitinib resistance through SREBP1/SCD1 signaling pathway - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6385389/#:~:text=match%20at%20L621%20inhibit%20the,resistance%20via%20SREBP1%2FSCD1%20signaling%20pathway')
51. AnnotationURLCitation(end_index=19709, start_index=19542, title='Glycerol kinase 5 confers gefitinib resistance through SREBP1/SCD1 signaling pathway - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6385389/#:~:text=We%20demonstrated%20that%20GK5%20confers,to%20EGFR%20tyrosine%20kinase%20inhibitors')
52. AnnotationURLCitation(end_index=20274, start_index=20107, title='Glycerol kinase 5 confers gefitinib resistance through SREBP1/SCD1 signaling pathway - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6385389/#:~:text=We%20demonstrated%20that%20GK5%20confers,to%20EGFR%20tyrosine%20kinase%20inhibitors')
53. AnnotationURLCitation(end_index=20872, start_index=20705, title='Glycerol kinase 5 confers gefitinib resistance through SREBP1/SCD1 signaling pathway - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6385389/#:~:text=We%20demonstrated%20that%20GK5%20confers,to%20EGFR%20tyrosine%20kinase%20inhibitors')
54. AnnotationURLCitation(end_index=21791, start_index=21616, title='Complete Inactivation of Sebum-Producing Genes Parallels the Loss of Sebaceous Glands in Cetacea | Molecular Biology and Evolution | Oxford Academic', type='url_citation', url='https://academic.oup.com/mbe/article-abstract/36/6/1270/5415914#:~:text=lineages%2C%20including%20the%20iconic%20Cetacea,Partial%20loss%20profiles%20were')
55. AnnotationURLCitation(end_index=22310, start_index=22162, title='R859 | Glycerol Kinase 5 (GK5)- Cloud-Clone Corp.', type='url_citation', url='http://www.cloud-clone.com/items/R859.html#:~:text=Glycerol%20Kinase%205%20%28GK5%29%20,Glycerol%20kinase%20catalyzes%20the')
56. AnnotationURLCitation(end_index=23193, start_index=23033, title='Glycerol Kinase Drives Hepatic de novo Lipogenesis and Triglyceride Synthesis in Nonalcoholic Fatty Liver by Activating SREBP‐1c Transcription, Upregulating DGAT1/2 Expression, and Promoting Glycerol Metabolism - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11633478/#:~:text=Glycerol%20Kinase%20Drives%20Hepatic%20de,6%E2%80%9325%20mM%20glucose%20had')
57. AnnotationURLCitation(end_index=23351, start_index=23194, title='Glycerol Kinase Drives Hepatic de novo Lipogenesis and Triglyceride Synthesis in Nonalcoholic Fatty Liver by Activating SREBP-1c Transcription, Upregulating DGAT1/2 Expression, and Promoting Glycerol Metabolism - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/39418169/#:~:text=Glycerol%20Kinase%20Drives%20Hepatic%20de,expressed%20as%20mean%20%C2%B1%20SEM')
58. AnnotationURLCitation(end_index=24027, start_index=23910, title='GK5 | Abcam', type='url_citation', url='https://www.abcam.com/en-us/targets/gk5/23412#:~:text=Skin,processing%20and%20lipid%20biosynthesis')
59. AnnotationURLCitation(end_index=24467, start_index=24323, title='Skin-specific regulation of SREBP processing and lipid biosynthesis by glycerol kinase 5 - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5495269/#:~:text=expressed%20predominantly%20in%20sebaceous%20glands,specific')
60. AnnotationURLCitation(end_index=24799, start_index=24633, title='Skin-specific regulation of SREBP processing and lipid biosynthesis by glycerol kinase 5 - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5495269/#:~:text=of%20cholesterol%20regulation%20in%20other,other%20skin%20lipids%20are%20necessary')
61. AnnotationURLCitation(end_index=24939, start_index=24800, title='Skin-specific regulation of SREBP processing and lipid biosynthesis by glycerol kinase 5 - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5495269/#:~:text=The%20recessive%20N,nucleus%20and%20led%20to%20elevated')
62. AnnotationURLCitation(end_index=25320, start_index=25138, title='Skin-specific regulation of SREBP processing and lipid biosynthesis by glycerol kinase 5 - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5495269/#:~:text=regulatory%20domains%2C%20inhibiting%20SREBP%20processing,regulation%20elsewhere%20in%20the%20body')
63. AnnotationURLCitation(end_index=25472, start_index=25321, title='Skin-specific regulation of SREBP processing and lipid biosynthesis by glycerol kinase 5 - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5495269/#:~:text=match%20at%20L681%20lipid%20synthesis,to%20bind%20to%20each%20other')
64. AnnotationURLCitation(end_index=25828, start_index=25656, title='Glycerol kinase 5 confers gefitinib resistance through SREBP1/SCD1 signaling pathway - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6385389/#:~:text=match%20at%20L621%20inhibit%20the,resistance%20via%20SREBP1%2FSCD1%20signaling%20pathway')
65. AnnotationURLCitation(end_index=25996, start_index=25829, title='Glycerol kinase 5 confers gefitinib resistance through SREBP1/SCD1 signaling pathway - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6385389/#:~:text=We%20demonstrated%20that%20GK5%20confers,to%20EGFR%20tyrosine%20kinase%20inhibitors')
66. AnnotationURLCitation(end_index=26870, start_index=26699, title='Skin-specific regulation of SREBP processing and lipid biosynthesis by glycerol kinase 5 - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5495269/#:~:text=We%20discovered%20a%20previously%20unrecognized,other%20skin%20lipids%20are%20necessary')
67. AnnotationURLCitation(end_index=27015, start_index=26871, title='Skin-specific regulation of SREBP processing and lipid biosynthesis by glycerol kinase 5 - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5495269/#:~:text=expressed%20predominantly%20in%20sebaceous%20glands,specific')
68. AnnotationURLCitation(end_index=27318, start_index=27147, title='Skin-specific regulation of SREBP processing and lipid biosynthesis by glycerol kinase 5 - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5495269/#:~:text=We%20discovered%20a%20previously%20unrecognized,other%20skin%20lipids%20are%20necessary')
69. AnnotationURLCitation(end_index=27463, start_index=27319, title='Skin-specific regulation of SREBP processing and lipid biosynthesis by glycerol kinase 5 - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5495269/#:~:text=expressed%20predominantly%20in%20sebaceous%20glands,specific')
70. AnnotationURLCitation(end_index=27746, start_index=27574, title='Glycerol kinase 5 confers gefitinib resistance through SREBP1/SCD1 signaling pathway - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6385389/#:~:text=We%20found%20that%20the%20exosomal,apoptosis%20via%20SREBP1%2FSCD1%20signaling%20pathway')
71. AnnotationURLCitation(end_index=27914, start_index=27747, title='Glycerol kinase 5 confers gefitinib resistance through SREBP1/SCD1 signaling pathway - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6385389/#:~:text=We%20demonstrated%20that%20GK5%20confers,to%20EGFR%20tyrosine%20kinase%20inhibitors')