What Is GID4? Biological Background

GID4 (also known as C17orf39) is a protein encoded by the GID4 gene in humans. It functions as the primary substrate-recognition receptor of the GID/CTLH (glucose-induced degradation/C-terminal to LisH) E3 ubiquitin ligase complex. The GID/CTLH complex is the mammalian ortholog of the yeast Gid complex, which was originally identified as a regulator of gluconeogenic enzyme degradation during the glucose-induced transition in Saccharomyces cerevisiae.

In the context of the ubiquitin-proteasome system (UPS), GID4 specifically recognizes substrates bearing a Pro/N-degron — a protein degradation signal defined by an N-terminal proline or a proline exposed after initiator methionine cleavage. By docking onto these N-terminal proline residues, GID4 recruits substrates to the GID/CTLH complex, which then catalyzes their polyubiquitination and subsequent proteasomal degradation. This selective recognition mechanism places GID4 at the heart of the Pro/N-degron branch of the broader N-degron pathway.

Dysregulation of GID4-dependent substrate turnover has been linked to cell cycle progression, metabolic reprogramming, and potentially oncogenic processes, making GID4 a subject of significant interest in both basic and translational research.

Protein Features and Production

The Recombinant Human GID4 Protein (SKU: rp372882) offered by Aladdin Scientific is produced using recombinant expression systems to ensure high purity and batch-to-batch consistency. Key considerations for researchers include:

• Recombinant origin: Produced via heterologous expression, avoiding the variability associated with tissue-purified material.
• Human sequence: Reflects the native human GID4 sequence, ensuring relevance to human cell biology studies.
• Intended use: Designed for in vitro research applications; not intended for therapeutic, diagnostic, or in vivo use.

For precise molecular weight, formulation buffer, purity grade, storage conditions, and lot-specific data, researchers should consult the Certificate of Analysis (CoA) supplied with each lot and the detailed product datasheet available from Aladdin Scientific.

Research Applications

Recombinant Human GID4 Protein is a versatile reagent suited to a range of biochemical and cell-biological experiments:

• Substrate identification: Used in pull-down or co-immunoprecipitation assays to identify novel Pro/N-degron substrates that bind the GID4 substrate-recognition domain.
• Biochemical assays: Suitable for ELISA-based interaction assays, surface plasmon resonance (SPR), and isothermal titration calorimetry (ITC) to characterize GID4–substrate binding kinetics and affinity.
• Structural studies: Applicable in X-ray crystallography or cryo-EM studies aimed at resolving GID4 structure alone or in complex with substrates or other GID/CTLH subunits.
• Reconstituted ubiquitination assays: Can be incorporated into in vitro ubiquitination reaction systems alongside E1, E2, and other GID/CTLH complex components to study substrate polyubiquitination.
• Drug discovery: Useful as a target protein in small-molecule or peptide inhibitor screening campaigns aimed at modulating the Pro/N-degron pathway.

Researchers studying cell cycle regulation, metabolic signaling, or targeted protein degradation (PROTAC) strategies may find GID4 particularly relevant as a hijackable E3 ligase component.

Handling, Storage, and Quality Considerations

To maintain protein integrity and experimental reproducibility, the following general best practices are recommended when working with Recombinant Human GID4 Protein:

• Storage: Store according to the conditions specified in the product datasheet and CoA. Recombinant proteins are generally stored at −80 °C for long-term preservation. Avoid repeated freeze-thaw cycles, which can lead to aggregation and loss of activity.
• Aliquoting: Upon first thaw, aliquot the protein into single-use volumes to minimize freeze-thaw stress.
• Handling: Keep on ice during use. Minimize exposure to room temperature. Use low-protein-binding tubes to reduce adsorption losses.
• Quality verification: Verify protein integrity by SDS-PAGE and confirm activity using an appropriate functional assay before critical experiments.
• Buffer compatibility: Consult the datasheet to ensure compatibility between the supplied formulation buffer and your downstream assay conditions. Dialysis or buffer exchange may be required for certain applications.

Note: Specific storage temperatures, formulation details, purity percentages, and activity data are lot-dependent. Always refer to the CoA provided with your specific lot.

GID4 in the Context of Targeted Protein Degradation

The emerging field of targeted protein degradation (TPD) has generated substantial interest in harnessing E3 ubiquitin ligases to degrade disease-relevant proteins of interest. GID4, as a ligand-accessible substrate receptor within the GID/CTLH complex, has attracted attention as a potential E3 ligase handle for PROTAC (Proteolysis-Targeting Chimera) and molecular glue strategies.

Because GID4 recognizes a defined structural feature — an N-terminal proline — it presents a tractable binding pocket for small-molecule ligand design. Researchers have begun exploring GID4-based PROTACs that exploit this recognition pocket to recruit neo-substrates (proteins of interest that do not naturally bear a Pro/N-degron) to the GID/CTLH complex, thereby directing their ubiquitination and degradation.

This application positions Recombinant Human GID4 Protein as a valuable biochemical tool not only for fundamental N-degron pathway research but also for the rapidly expanding TPD drug discovery pipeline. Laboratories engaged in chemical biology, medicinal chemistry, or cancer biology may benefit from incorporating this protein into their research toolkit.