CD4 Proteins

CD4 is a type I transmembrane glycoprotein expressed on the surface of T cells (also known as T-cell surface antigen T4/Leu-3). The extracellular domain contains four Ig-like domains and plays a central role in MHC class II–mediated antigen recognition and T cell activation. CD4 also functions as the receptor for interleukin-16 (IL-16) and is the primary receptor for HIV envelope glycoprotein mediating HIV entry , making it an important target for immunology, infectious disease, and therapeutic research. Conigen provides recombinant CD4 proteins designed to support binding studies, assay development, and antibody discovery.

Anti-human CD4 Antibody Binding

Example QC data shown. See individual product pages and datasheets for target-specific QC results.

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Available formats

Soluble CD4 ectodomain dimer CSPâ„¢ (Conigen Soluble Protein)

  • Human
  • Rhesus macaque

Available tags

  • His
  • His-Avi
  • Biotinylated (His-Avi)

Available CD4 Products

ProductTagSpeciesProduct CodeDetailshf:tax:product_taghf:tax:pa_species
Biotinylated CD4His-AviBCSP-24004-03Show detailshis-avi
CD4HisCSP-24004Show detailshis
CD4His-AviCSP-24004-03Show detailshis-avi
CD4HisRhesus MacaqueCSP-24038Show detailshisrhesus-macaque

Applications

  • Antibody discovery and characterization (ELISA screening and specificity testing for CD4-targeting antibodies)
  • HIV gp120 binding studies (ELISA and SPR workflows to evaluate CD4–gp120 interactions, including competition/blocked-binding formats)
  • Binding kinetics and affinity measurements (BLI assays for interaction measurement and ranking of CD4-binding reagents)
  • Cell-based workflows (B cell sorting and reagent development using CD4-binding tools)
  • Animal immunization (RUO) (as an immunogen to support generation of CD4-targeting antibodies)

Quality Control and Specifications

Quality Control Testing

  • Purity assessment (greater than 90% dimer formed as determined by SDS-PAGE under reducing and non-reducing conditions).
  • Bioactivity testing (binding activities confirmed by ELISA, BLI and SPR for HIV-1 envelope glycoproteins, and CD4-specific antibody interactions, with reported EC50 and KD ranges).
  • Lot-specific documentation provided in downloadable product datasheets.

Product Specifications

  • Format: extracellular domain cis-dimers of CD4 
  • Expression host: HEK293T (mammalian)
  • Construct: soluble extracellular domain (ECD) dimer fused with a proprietary dimer motif to mimic the native conformation
  • Formulation: 0.22 μm filtered PBS, pH 7.4
  • Storage & shipping: shipped frozen on dry ice; store at −80°C

About Conigen Soluble Proteins

Engineered dimeric proteins with quaternary structures

  • Enhances receptor/ligand binding
  • Increase functional activity
  • Improve binding avidity for better detection sensitivity
  • Compact size dimer motif
  • Fc-free to avoid FcR binding
  • Glycan-free dimer motifs to avoid target epitope masking

 

Learn more about the CSPâ„¢ (Conigen Soluble Protein) Platform

Choosing the right CD4 format

Biotinylated vs Standard

Choose a biotinylated format if you:

  • perform flow cytometry
  • need immobilization for SPR, or BLI
  • want controlled orientation of the soluble protein
  • require consistent epitope presentation

 

Choose a standard (non-biotinylated) format if you:

  • perform both solid-phase and solution-phase binding or screening assays
  • Perform SPR, BLI 
  • want the simplest protein format
  • HIV neutralization assays

FAQs

Recombinant CD4 is widely used as a research tool to study immune function, receptor-ligand interactions, and disease mechanisms, particularly in immunology and infectious disease research. Common applications include:

  • Binding and interaction studies (ELISA, SPR, BLI)
  • Antibody screening and validation
  • CD4-specific B cell flow cytometry analysis and sorting
  • HIV research
  • Assay and reagent development

Our CD4 is provided as a dimer and engineered to replicate the native, cell-surface conformation of CD4 more closely than the monomeric ectodomain.

In practice, our dimeric CD4 provides:

  • Higher binding potency
  • Improved assay sensitivity 
  • Wider assay windows

Yes, our recombinant CD4 has been validated for use in binding assays, including CD4-antibody specific binding assays and HIV envelope glycoprotein binding assays by ELISA, SPR, BLI. It demonstrates reliable and specific binding performance under standard ELISA, SPR, and BLI conditions.

CD4 is supplied in PBS and is shipped on dry ice. Upon receipt, it should be stored in a -80 freezer. For optimal stability we recommend aliquoting the protein into smaller volumes before freezing to avoid repeated freeze-thaw cycles.

For short term use, the protein may be stored at 4°C for a limited period. For long-term storage, keep the protein in a -80 freezer for up to 12 months. Avoid vigorous mixing; gently invert or pipette to mix if needed.

Conigen offers CD4 proteins in multiple tag formats, including His-tagged and His-Avi-tagged and biotinylated catalog dimers. 

 

Additional tags such as Fc, Flag, HA, or Myc can be provided through custom expression to match your assay or conjugation needs.

Yes. CD4 proteins can be customized through Conigen’s CSP â„¢ platform. For custom CD4 formats (alternate tags, variants, or assay-specific constructs), email [email protected] or submit a request through our Custom Project form.

Lead time varies by format and scale. Catalog CD4 can be ordered directly and will ship within 2-3 business days of sales order receipt. 


Custom CD4 and larger orders will follow a defined project workflow, but will generally be shipped 4-6 weeks following request. Contact us for a precise delivery estimate.

Need help selecting the right CD4 protein format for your assay?

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