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C4 Protein

For Research Use Only. Not for use in diagnostic procedures.

Purified human complement component C4. C4 is one of the proteins unique to the Classical Complement Pathway. The 200 kD C4 protein is made up of three peptide chains linked by disulfide bonds and contains a thioesterbond. When the classical pathway is activated, C1s cleaves C4 to C4a (a weak anaphylatoxin) and C4b. C4b can then bind covalently to a target surface or complex. It can then function as an opsonin or participate as part classical pathway convertase. C4 has been shown to exist as two separate "complotypes" C4A and C4B. These have been shown to have different biological properties.

All Quidel complement components are tested for functional activity in a standard lytic or applicable functional assay and for biochemical purity by SDS-polyacrylamide gel electrophoresis. Please refer to the Certificate of Analysis for lot specific information on functional titer.

Quidel's purified human complement components are useful in a wide variety of immunochemical and research applications. For assistance with a specific protocol, please contact Quidel Technical Support.


Schifferli JA, Paccaud J. Two Isotypes of human C4, C4A and C4B, have different structure and function, Complement and Inflammation 6:19-26, 1989.

Nicholson-Weller, Butko, P, Wessels, M. Role of Complement Component C1q in IgG Independent Opsonophagocytosis of Group B Streptococcus, J. Immunol 163:2761-2768, 1999.

Features & Benefits


Product Specifications

Product Spec NameProduct Spec Data

1.0 mg/mL


250 µL/vial


At or below –70°C


> 90%



Ordering Information

Catalog NumberKit Size / Case Size
250 µL/vial

Product Documentation

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