PIK3R4 Antibody / Phosphoinositide 3-kinase regulatory subunit 4

Overview

PIK3R4 Antibody / Phosphoinositide 3-kinase regulatory subunit 4 is an antibody targeting PIK3R4, raised in Rabbit for protein detection and localization studies where these specifications are required.

Key elements and design rationale

• Target: PIK3R4.
• Antibody identity: Polyclonal (rabbit origin); Rabbit IgG.
• Conjugate/label: Unconjugated (affects detection chemistry and multiplex compatibility).
• Format: Antigen affinity purified.
• Species reactivity: Human.
• Listed applications: WB, FACS, ELISA (refer to on-page specifications for application-specific guidance).

Biological background

Phosphoinositide 3-kinase regulatory subunit 4, also known as PI3-kinase regulatory subunit 4 or PI3-kinase p150 subunit or phosphoinositide 3-kinase adaptor protein, or VPS15 is an enzyme that in humans is encoded by the PIK3R4 gene. The serine/threonine PI3 kinase regulatory subunit 4 (PIK3R4, Vps15) is the mammalian homologue of the yeast vacuolar protein sorting 15. PIK3R4 regulates the kinase activity of PI3K class III and anchors the kinase to cellular membranes through myristoylation. Recruitment of PI3K class III to the site of early endosome fusion and docking is directly mediated by PIK3R4 binding to the small GTPase Rab5 through its HEAT and WD-40 domains. The PIK3R4/PI3K class III plays a role in late endosome function through PIK3R4 binding to the Rab7 GTPase. In addition to its role in trafficking, the PIK3R4/PI3K class III complex interacts with beclin-1 to play a role during several stages of autophagy. Autophagosome formation is stimulated when Atg14 complexes with PIK3R4, PI3K class III, and beclin-1. The UVRAG protein competes with Atg14 for beclin-1 binding, forming a mutually exclusive complex with PIK3R4, PI3K class III, and beclin-1 that regulates autophagosome maturation. Autophagosome maturation is impaired in the presence of the beclin-1-binding protein Rubicon. Co-expression of PIK3R4 is required for PI3K class III activation and regulation by both beclin-1/UVRAG and by nutrients. Overexpression of PIK3R4 protein has been associated with decreased survival in patients with ovarian tumors, while mutations of the corresponding PIK3R4 gene are associated with metastatic melanoma, suggesting that PIK3R4 functions in cancer.

Research relevance and current trends

• Comparative expression profiling across cell types, tissues, or perturbations (e.g., drug treatment, genetic editing, or differentiation).
• Subcellular localization and trafficking studies, including co-localization with pathway markers in microscopy-based assays.
• Integration of protein-level measurements with transcriptomics or proteomics to relate abundance to regulation and phenotype.

Common research applications

• Western blotting: researchers commonly compare relative signal levels across conditions and use appropriate negative/positive controls for interpretation.
• Flow cytometry: researchers commonly compare relative signal levels across conditions and use appropriate negative/positive controls for interpretation.
• ELISA: researchers commonly compare relative signal levels across conditions and use appropriate negative/positive controls for interpretation.

Interpretation should account for antibody-dependent factors such as epitope accessibility, isoforms, and sample preparation differences across workflows.

Notes for experimental interpretation

• Isoforms and PTMs: many targets have multiple isoforms and post-translational modifications that can shift apparent signal or localization; interpret bands/signals accordingly.
• Epitope context: binding can depend on protein conformation and sample processing; region information in the title/immunogen can help anticipate what may be detected.
• Species differences: predicted or validated reactivity may vary by ortholog sequence and sample context; confirm in your model system.
• Control concepts: include negative controls (no-primary/isotype), and where possible genetic controls (KO/KD) or independent antibodies to strengthen conclusions.

Customization & Add-ons: Can’t find the antibody you need—or require a custom format for your assay? We can help you source the best match or support custom antibody solutions for diverse research needs, including species and isotype selection, conjugations and labeling (e.g., HRP/AP, biotin, fluorophores), purification grade options (Protein A/G, affinity purified), formulation preferences (buffer selection, carrier-free, glycerol-free), custom concentrations and aliquoting, low-endotoxin options for cell-based work, and application-focused QC/validation support (project dependent). Click Talk to a Scientist to submit a request, email us at support@biohippo.com, or explore our Research Services for additional support—our team will follow up with feasibility details and next steps.