At PhosphoSolutions, an Antibodies Inc brand, we are committed to providing high-affinity, highly validated antibody tools for proteomic research. Produced by our custom antibody development team, our Anti-Phospho-GUK1 (Tyr74) Antibody was instrumental in a recent study published in Cell by the Haigis Lab at Harvard Medical School. The study highlights a metabolic dependency that may offer new possibilities for therapeutic intervention: the site-specific activation of Guanylate Kinase 1 (GUK1) via tyrosine phosphorylation.
The Study: GUK1 Tyr74 Phosphorylation as a Metabolic Switch
GUK1 activation is a metabolic liability in lung cancer. (Schneider et al., 2025). PMID: 39919745
Guanylate kinase 1 (GUK1) is a rate-limiting enzyme in the guanine nucleotide salvage pathway, facilitating the conversion of GMP to GDP. The study demonstrates that GUK1 activity is dynamically regulated by oncogenic tyrosine kinases, specifically Anaplastic Lymphoma Kinase (ALK).
Key findings from the study include:
- Site-Specific Activation: The study identified Tyr74 as a critical phosphorylation site. Phosphorylation at this residue by ALK significantly enhances GUK1 catalytic activity, thereby increasing the intracellular pool of GDP/GTP.
- Oncogenic Dependency: Utilizing CRISPR-Cas9 and phosphomimetic/null variants, the researchers established that the GUK1-Tyr74 axis is essential for maintaining Ras-GTP loading and downstream proliferative signaling in ALK-rearranged models.
- Therapeutic Implications: Genetic or pharmacological disruption of this metabolic node resulted in marked tumor regression in vivo, suggesting that GUK1 activation is a targetable metabolic liability in NSCLC.
The Model: In Vivo Engineering with Ad-EA EML4-ALK
In addition to the antibody highlighted in the recent Cell 2025 publication, the study also used a custom adenoviral vector developed by ViraQuest (another Antibodies Inc brand) - Ad-EA EML4-ALK - to enable CRISPR-Cas9 mediated generation of an autochthonous lung cancer model in vivo.
Originally engineered using our custom adenovirus services in collaboration with Andrea Ventura’s laboratory at Memorial Sloan Kettering Cancer Center, this adenovirus was first described in their landmark publication, “In vivo engineering of oncogenic chromosomal rearrangements with the CRISPR/Cas9 system” (Nature. 2014, PMID: 25337876). In this study, the viral vector was used to deliver CRISPR components in vivo to induce defined oncogenic rearrangements, enabling the generation of clinically relevant lung cancer models directly in mice.
Custom Reagents
Although Ad-EA EML4-ALK is not currently offered as an off-the-shelf catalog product, it remains available through ViraQuest/Antibodies Inc as a custom reagent. Access for research use is available upon approval from the originating laboratory, allowing investigators to utilize a well-established and widely cited modeling system for their own oncogene-driven research.
The Antibody: Anti-Phospho-GUK1 (Tyr74) Antibody
Proudly developed by our team of scientists in Davis, California, our Anti-Phospho-GUK1 (Tyr74) Antibody offers sensitive, phosphospecific signal in Western blot and is capable of detecting endogenous levels of phospho-GUK1 in various cancer cell lines and patient-derived xenograft (PDX) tissues.
Western blot detection of GUK1 phosphorylated at Tyr74 using anti-pGUK1 (Tyr74) rabbit polyclonal antibody (Cat. No. pGUK1-74). Whole-cell lysates from HEK293T cells co-expressing EML4-ALK with FLAG-GUK1-WT or FLAG-GUK1-Y74F were analyzed by SDS-PAGE and immunoblotting. The pGUK1-Y74 antibody (1:200) specifically detects GUK1-WT (~25 kDa) but not the Y74F mutant. Actin serves as a loading control. Image by Kiran Kurmi, University of Miami Miller School of Medicine.
The Custom Antibody Development Service
The development of the GUK1 Tyr74 antibody showcases the expertise available through our Custom Phosphospecific Antibody Development. Generating a high-affinity antibody against a single phosphorylated residue is a technical challenge that requires an expert approach to antigen design and purification.
Our team has been developing custom phosphospecific antibodies for over 20 years. Our service includes:
- Antigen Optimization: Analyzing protein structure to design the most effective phospho-peptide immunogen.
- Serum Screening: We collect and test multiple bleeds to find the highest titer serum.
- Sequential Affinity Chromatography: Phosphospecific antibodies are isolated using both phospho and non-phospho peptide columns removing non-phospho-reactive and pan-specific antibodies, ensuring site-specificity.
- Characterization: ELISA assays are performed on all purification fractions to ensure publication-ready results.
Ready to target a new phosphorylation site?
Partner with the team that developed the GUK1 Tyr74 antibody. Explore our Custom Phosphospecific Antibody Services and contact our scientists today to discuss your project.
References
- Schneider, J. L., Kurmi, K., et.al (2025). GUK1 activation is a metabolic liability in lung cancer. Cell. Mar 6;188(5):1248-1264.e23 (2025). PMID: 39919745
- Maddalo, D., Manchado, E., Concepcion, C. et al. In vivo engineering of oncogenic chromosomal rearrangements with the CRISPR/Cas9 system. Nature 516, 423–427 (2014). PMID: 25337876