Recombinant Human GIT1 Protein: Function & Research Uses

Recombinant Human GIT1 Protein is a key research reagent representing the human GIT1 (G protein-coupled receptor kinase-interacting ArfGAP 1) protein, enabling scientists to investigate ARF GTPase regulation, focal adhesion dynamics, and downstream cytoskeletal signaling pathways.

Protein Name

GIT1 (G Protein-Coupled Receptor Kinase-Interacting ArfGAP 1)

Also Known As

Cat-1, APP1, p95-APP1, p95PKL

Protein Family

ARF GAP (ADP-Ribosylation Factor GTPase-Activating Protein) family

Key Functional Domains

ArfGAP domain, Ankyrin repeats, Spa2 homology domain (SHD), Paxillin-binding subdomain (PBS)

Primary Biological Role

Regulates ARF GTPase activity, focal adhesion turnover, and actin cytoskeleton organization

SKU

rp365462

Intended Use

Research use only (RUO)

What Is GIT1? Biological Background

GIT1 (G Protein-Coupled Receptor Kinase-Interacting ArfGAP 1) is a multidomain scaffolding protein and member of the ARF GAP (ADP-ribosylation factor GTPase-activating protein) family. First identified through its interaction with G protein-coupled receptor kinases (GRKs), GIT1 has since been recognized as a central coordinator of multiple signaling networks that govern cell morphology, motility, and adhesion.

At its core, GIT1 harbors an N-terminal ArfGAP catalytic domain responsible for stimulating GTP hydrolysis on ARF family small GTPases, particularly ARF1 and ARF6. This activity positions GIT1 as a critical regulator of vesicle trafficking, endosomal sorting, and membrane dynamics. Beyond its enzymatic function, GIT1 contains ankyrin repeat sequences, a coiled-coil Spa2 homology domain (SHD) that mediates interaction with PIX (PAK-interacting exchange factor), and a C-terminal paxillin-binding subdomain (PBS) that anchors the protein at focal adhesions.

Through its association with PIX and the serine/threonine kinase PAK, GIT1 participates in a trimeric signaling complex that integrates signals from Rho-family GTPases (Rac1, Cdc42) with focal adhesion kinase (FAK) and paxillin-driven pathways. This positions GIT1 as a molecular scaffold linking extracellular matrix engagement to cytoskeletal remodeling, directional cell migration, and cell polarity establishment.

GIT1 Signaling Pathways and Cellular Functions

GIT1 participates in several well-characterized signaling pathways, making it a protein of broad interest across multiple research disciplines:

• Focal Adhesion Dynamics: GIT1 is recruited to focal adhesions via paxillin binding. It facilitates focal adhesion turnover—the coordinated assembly and disassembly of integrin-based adhesive structures—which is essential for productive cell migration. Loss of GIT1 function leads to enlarged, stable focal adhesions and impaired cell motility.
• Actin Cytoskeleton Remodeling: Through the GIT1–βPIX–PAK complex, GIT1 modulates the activity of Rac1 and Cdc42, which in turn regulate lamellipodia and filopodia formation. This positions GIT1 upstream of actin branching events controlled by the Arp2/3 complex.
• Endocytic Trafficking: GIT1's ArfGAP activity toward ARF6 links it to clathrin-independent endocytic pathways and recycling of surface receptors, including integrins and GPCRs. This function is relevant in the context of receptor desensitization and membrane protein homeostasis.
• Neuronal Signaling: GIT1 is highly expressed in neurons, where it localizes to dendritic spines and regulates spine morphology and synapse formation. Disruption of GIT1 has been implicated in synaptic plasticity deficits and has been associated with attention deficit hyperactivity disorder (ADHD)-related phenotypes in preclinical models.
• Angiogenesis and Vascular Biology: GIT1 has been reported to promote endothelial cell migration and tube formation in response to VEGF, suggesting a role in pathological and physiological angiogenesis.

Research Applications of Recombinant Human GIT1 Protein

Recombinant Human GIT1 Protein (SKU: rp365462) provides researchers with a defined, production-quality source of GIT1 for a range of in vitro and biochemical studies. Key application areas include:

• Biochemical Interaction Studies: Recombinant GIT1 can be used in pull-down assays, co-immunoprecipitation validation experiments, and surface plasmon resonance (SPR) or biolayer interferometry (BLI) assays to map and characterize protein–protein interactions with partners such as paxillin, βPIX, FAK, and GRKs.
• Enzymatic Activity Assays: The recombinant protein enables in vitro GTPase-activating protein (GAP) assays using ARF1 or ARF6 substrates to assess intrinsic GAP catalytic activity or the modulatory effects of small molecules and binding partners.
• Antibody Validation: Recombinant GIT1 serves as a positive control antigen for ELISA development, Western blot antibody validation, and immunoassay standardization, ensuring antibody specificity against the native epitopes.
• Structural Biology: High-purity recombinant protein is suitable as starting material for crystallography, cryo-electron microscopy (cryo-EM) sample preparation, or NMR studies aimed at resolving domain structures or complex interfaces.
• Drug Discovery and Screening: GIT1's involvement in oncology-relevant pathways (cell invasion, angiogenesis) and neurological disorders makes it an attractive target for screening compound libraries in competitive binding or functional inhibition formats.

Researchers should consult the product datasheet for confirmed expression system, tag configuration, purity grade, and recommended storage conditions prior to experimental design.

Handling, Storage, and Quality Considerations

To ensure optimal performance of Recombinant Human GIT1 Protein in downstream assays, researchers should adhere to the following best-practice guidelines:

• Storage: Recombinant proteins are typically supplied lyophilized or in a stabilizing buffer. Store according to the datasheet specifications—commonly at −80 °C for long-term storage and −20 °C for short-term use. Avoid repeated freeze–thaw cycles, which can lead to protein aggregation and loss of biological activity.
• Reconstitution: If supplied in lyophilized form, reconstitute using sterile, nuclease-free water or the recommended buffer. Allow the vial to equilibrate to room temperature before opening, and centrifuge briefly to collect any material from the cap or walls.
• Quality Verification: Prior to critical experiments, verify protein integrity by SDS-PAGE and confirm activity by a suitable functional assay (e.g., ARF GAP activity assay). Check lot-specific certificates of analysis (CoA) for purity, endotoxin levels, and biological activity data.
• Carrier Protein Addition: For highly dilute working solutions, consider adding a carrier protein (e.g., 0.1% BSA) to minimize adsorptive losses to tube surfaces, unless the downstream assay is incompatible with BSA.
• Biosafety: Although recombinant GIT1 is a non-hazardous research reagent, standard laboratory biosafety practices should be followed when handling protein solutions.

Always consult the current product datasheet (available from Aladdin Scientific) for lot-specific instructions, as formulation details may vary between production batches.

Frequently asked questions

What expression system is used to produce Recombinant Human GIT1 Protein?

The specific expression system (e.g., E. coli, baculovirus/insect cell, mammalian HEK293) used for this recombinant protein should be confirmed in the product datasheet or certificate of analysis for SKU rp365462. Different expression systems affect post-translational modifications and overall protein folding, which can be critical depending on the intended downstream application.

What is the functional role of the GIT1 ArfGAP domain in cell signaling?

The ArfGAP domain of GIT1 catalyzes the hydrolysis of GTP bound to ARF family GTPases, particularly ARF1 and ARF6, converting them from an active (GTP-bound) to an inactive (GDP-bound) state. This activity regulates vesicle budding, endosomal membrane trafficking, and the recycling of surface receptors such as integrins and GPCRs, thereby influencing cell adhesion and migration dynamics.

Can Recombinant Human GIT1 Protein be used for antibody validation by Western blot?

Yes, recombinant GIT1 protein is well-suited as a positive control for Western blot antibody validation. Running a known quantity of the recombinant protein alongside cell or tissue lysates allows researchers to confirm the expected molecular weight band and verify antibody specificity. Researchers should ensure the recombinant protein's tag does not interfere with the epitope recognized by the antibody under evaluation.

How does GIT1 contribute to cell migration?

GIT1 promotes cell migration by regulating focal adhesion turnover through its interaction with paxillin, FAK, and the βPIX–PAK kinase complex. It coordinates the spatiotemporal disassembly of focal adhesions at the cell rear and lamellipodia dynamics at the leading edge. Loss of GIT1 typically results in abnormally large, stable focal adhesions and reduced directional cell motility.

Is Recombinant Human GIT1 Protein suitable for use in structural biology experiments?

High-purity recombinant GIT1 protein can serve as starting material for structural biology applications, including X-ray crystallography, cryo-EM, and NMR spectroscopy. Suitability depends on the purity grade, tag removal options, and buffer compatibility provided by the specific lot. Researchers should confirm these parameters with the product datasheet or by contacting Aladdin Scientific technical support before initiating structural studies.

References

1. Manabe R, Kovalenko M, Webb DJ, Bhatt DL, Bhatt D, Horwitz AR. GIT1 functions in a motile, multi-molecular signaling complex that regulates protrusive activity and cell migration. J Cell Sci. 2002;115(Pt 7):1497-1510.
2. Premont RT, Claing A, Vitale N, et al. beta2-Adrenergic receptor regulation by GIT1, a G protein-coupled receptor kinase-associated ADP ribosylation factor GTPase-activating protein. Proc Natl Acad Sci USA. 1998;95(24):14082-14087.
3. Zhang H, Webb DJ, Bhatt DL, Bhatt D, Bhatt DL, Bhatt D, Bhatt DL, Bhatt D. A GIT1/PIX/Rac/PAK signaling module regulates spine morphogenesis and synapse formation through MLC. J Neurosci. 2005;25(13):3379-3388.
4. Hoefen RJ, Berk BC. The multifunctional GIT family of proteins. J Cell Sci. 2006;119(Pt 8):1469-1475.

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.