What Is GPSM3? Gene and Protein Background

GPSM3 (G-Protein Signaling Modulator 3), also known as AGS4 (Activator of G-Protein Signaling 4), is a member of the GPSM protein family. These proteins are characterized by the presence of one or more GoLoco motifs, short peptide sequences that interact with the GDP-bound form of Gα subunits of heterotrimeric G-proteins.

The GPSM3 gene encodes a relatively small cytoplasmic protein that functions as a guanine nucleotide dissociation inhibitor (GDI) for Gαi subunits. By stabilizing the GDP-bound, inactive state of Gα, GPSM3 modulates the availability of free Gβγ dimers and thereby influences downstream G-protein-coupled receptor (GPCR) signaling cascades.

Expression of GPSM3 has been reported in immune cells, including neutrophils, suggesting a potential role in immune cell function and inflammatory signaling. As with other GPSM family members, GPSM3 may participate in the non-canonical regulation of cell polarity, migration, and asymmetric cell division, though the full scope of its biological roles remains an area of active investigation.

Biochemical Properties of Recombinant Human GPSM3 Protein

Recombinant Human GPSM3 Protein (SKU: rp371436) is produced using recombinant protein expression technology to deliver a research-grade reagent suitable for in vitro studies. Key biochemical characteristics of GPSM3 relevant to its use as a research tool include:

• GoLoco Motif Activity: The protein contains a GoLoco (or GPR) motif that binds directly to GDP-loaded Gαi family subunits, inhibiting spontaneous GDP release and thus locking Gα in an inactive conformation.
• Selectivity: GPSM3 exhibits selectivity for Gαi subfamily members over other Gα classes, a feature shared with other GoLoco-containing proteins.
• Cytoplasmic Localization: As a cytoplasmic protein, GPSM3 acts at the intracellular interface of G-protein signaling, independent of direct membrane anchoring.

Researchers should consult the product datasheet for lot-specific information including purity, molecular weight, formulation, storage conditions, and recommended reconstitution procedures.

Research Applications

Recombinant Human GPSM3 Protein is a versatile tool for researchers investigating G-protein signaling and related biology. Representative research applications include:

• In Vitro Binding Assays: Study direct protein–protein interactions between GPSM3 and Gαi subunits using pull-down, co-immunoprecipitation, or surface plasmon resonance (SPR) assays.
• Enzyme Activity Modulation Studies: Assess the capacity of GPSM3 to inhibit GTPase activity or nucleotide exchange on Gαi subunits in biochemical assays.
• Cell-Free Reconstitution Systems: Use recombinant GPSM3 to reconstitute and study G-protein regulatory circuits in defined, cell-free systems.
• Structural Biology: Employ the purified recombinant protein as a component in crystallography or cryo-EM studies of GoLoco–Gα complexes.
• Antibody Validation: Use as a positive control antigen for validating GPSM3-specific antibodies in western blot or ELISA formats.
• Immune Cell Signaling Research: Investigate the role of GPSM3 in GPCR signaling in neutrophils or other immune cell contexts.

All applications should be performed under conditions appropriate for research use only. Aladdin Scientific recommends optimizing experimental conditions empirically for each specific application.

Handling, Storage, and Quality Considerations

To maintain the activity and integrity of Recombinant Human GPSM3 Protein, researchers should adhere to the following best-practice guidelines:

• Storage: Store according to the conditions specified on the product datasheet. Recombinant proteins are typically stored at −80 °C for long-term preservation. Avoid repeated freeze–thaw cycles, which can lead to protein aggregation and loss of activity.
• Reconstitution: Reconstitute lyophilized protein in the recommended buffer and volume as stated on the datasheet. Allow the vial to equilibrate to room temperature before opening.
• Working Aliquots: Prepare single-use aliquots after reconstitution to minimize freeze–thaw cycling.
• Quality Control: Each lot of Recombinant Human GPSM3 Protein from Aladdin Scientific is subject to quality control testing. Refer to the Certificate of Analysis (CoA) for lot-specific purity and activity data.
• Safety: Handle as a potential biological reagent; follow your institution's biosafety guidelines for recombinant protein handling.

For lot-specific storage instructions, purity grades, and formulation details, always refer to the product datasheet and CoA supplied with the product.