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Human HER2 (CD340) Protein (C-His-Avi)

Human Her2 Protein (C-His-Avi) on SDS-PAGE under reducing condition (P+) and non-reducing condition (P-). The gel was stained for 1 hour with BlinkBlue (catalog 700102). The purity of this protein appears to be greater than 95%.

Cat #	Size	Price	Quantity
804101	25 ug	$145
804102	100 ug	$295

Bulk/Custom

Product Details

Application	ELISA, BLI
Format	Liquid, Purified
Expression Host	CHO
Target Name	HER2, HER-2, ERBB2, CD340, neu, MLN19, NEU, NGL, TKR1
Species	Human
Sources	Recombinant Human Her2 protein (Thr23-Thr652) with C-terminus His-Avi tag is expressed in CHO cells.
Accession Number	P04626
Molecular Weight	The protein has a predicted molecular weight of 73 kDa. Under DTT-reducing conditions, it migrates at approximately 85 kDa on SDS-PAGE.
Affinity Tag	C-His-Avi
Purity	>95% based on SDS-PAGE under reducing condition
Regulatory Status	RUO
Formulation	1xPBS buffer, pH7.4, 0.22 µm filtered
Endotoxin level	Not tested
Protein Concentration	25µg size is bottled at 0.2mg/mL concentration. 100 µg size is supplied at a lot-specific concentration.
Storage and Handling	Briefly centrifuge the vial upon receipt. An unopened vial can be stored at 4°C for up to 2 weeks, or at -20°C or below for up to six months. The protein may be further diluted to 0.1 mg/mL using 0.22 µm-filtered PBS buffer (pH 7.4). For long-term storage, the diluted stock solution should be aliquoted and stored at ≤ –70°C to minimize freeze-thaw cycles. If additional dilution is required, carrier proteins such as FBS or BSA should be added to maintain protein stability.
Research Areas	Mesenchymal Stem Cells, Embryogenesis, Cancer Marker, Cancer Immunology

Background Information

HER2 (Human Epidermal Growth Factor Receptor 2), also known as ERBB2 or CD340, is a transmembrane protein that plays a pivotal role in normal cell growth and differentiation. It is a member of the epidermal growth factor receptor (EGFR/ERBB) family of receptor tyrosine kinases. Under normal physiological conditions, HER2 is expressed at low levels on the surface of epithelial cells, where it helps regulate cell proliferation and survival signals. However, its primary fame in medicine comes from its potent ability to drive uncontrolled cell growth when the gene encoding it is amplified or the protein is overexpressed.

Structurally, HER2 consists of an extracellular ligand-binding domain, a transmembrane spanning region, and an intracellular tyrosine kinase domain. A unique and critical feature of HER2 is that it is an "orphan receptor," meaning it has no known direct ligand. Unlike other family members (EGFR, HER3, HER4) that require a growth factor to bind and activate them, HER2 exists in a constitutively open conformation, ready to interact. It functions by forming heterodimers with other ligand-bound members of the HER family. This makes HER2 the preferred dimerization partner for all other ERBB receptors, amplifying the signaling strength of the network significantly.

In the context of disease, HER2 is a major driver of tumorigenesis. Gene amplification leads to the overexpression of HER2 proteins on the cell surface, sometimes up to 100 times the normal level. This results in spontaneous dimerization and continuous, ligand-independent firing of growth signals, leading to aggressive cell division and resistance to apoptosis. HER2 overexpression is most notably observed in approximately 15-20% of breast cancers and a significant subset of gastric and gastroesophageal cancers, classifying them as "HER2-positive."

Therapeutically, HER2 is one of the most successful targets in the history of precision oncology. The development of trastuzumab (Herceptin), a monoclonal antibody that binds to the extracellular domain of HER2, revolutionized treatment by blocking downstream signaling and flagging cells for immune destruction. Therapy has since evolved to include dimerization inhibitors like pertuzumab, small-molecule tyrosine kinase inhibitors (TKIs) like lapatinib that work inside the cell, and antibody-drug conjugates (ADCs) like T-DM1 and trastuzumab deruxtecan. These ADCs use the HER2 antibody as a "Trojan horse" to deliver potent chemotherapy directly into the cancer cell, sparing healthy tissue.

Frequently Asked Questions

How is a fluorescence labeled recombinant protein different from a labeled antibody for the same target?

A labeled protein (e.g., a fluorescent ligand or receptor domain) binds its natural counter-receptor or binding partner directly, making it useful for functional binding assays, competition/blocking studies, and receptor occupancy measurements — whereas an antibody typically binds a specific epitope regardless of the protein's natural binding activity. Choose the labeled protein format when you need to assess biologically relevant binding interactions rather than simple target detection.

Can these proteins be used in flow cytometry, and are they compatible with other panel reagents?

Yes, fluorescence labeled proteins are commonly used in flow cytometry panels to detect receptor expression or ligand binding on live cells, and are designed to be compatible with standard antibody panels. As with any multicolor panel, confirm spectral compatibility and run proper compensation controls when combining labeled proteins with labeled antibodies.

What controls should I use with fluorescence labeled recombinant proteins?

Recommended controls include an unlabeled/unconjugated version of the same protein (for competition/blocking controls), an irrelevant labeled protein of the same conjugate as a background control, and standard unstained/FMO controls for gating. Species- or format-matched controls are noted on the product page where available.

What applications are these proteins validated for?

Common applications include receptor binding assays, flow cytometry-based ligand-receptor studies, ELISA-based detection, and blocking/competition assays to study receptor occupancy or antagonist activity. Specific validated applications and recommended usage concentrations vary by product and are detailed on the individual product page.

Have a product or application question? Consult our FAQs or contact us.

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