Overview:

An immunoglobulin (Ig) binding protein, Protein A (SpA) is present on the surface of bacteria and secreted into the extracellular environment. Protein A is known to bind the Fab regions, B-cell receptor (IgM), and Fc region of antibody in the host cell and suppresses host cell immune responses (1,2). Such cross-linking is found to prevent opsonophagocytosis and result in B-cell death in vitro (2). In most cases, protein A binds IgG but in certain species the binding is restricted to IgG subclasses. This characteristic enables efficient immunoglobulin purification and analysis, and fractionation of antibody subclasses (3). Overall, protein A can be used as an immunological reagent in a broad range of studies that involve detection of antibody-secreting cells (4).

Gene Aliases:

SpA

Genebank Number:

CAE54483.1

Formulation:

Recombinant protein stored in 50mM sodium phosphate, pH 7.5, 300mM NaCl, 300mM imidazole.

References:

1. Kim, HK, et al. Protein A suppresses immune responses during Staphylococcus aureus bloodstream infection in guinea pigs. 2015, MBio 6.1: e02369-14.

2. Dossett, JH., et al. Antiphagocytic effects of staphylococcal protein A.The Journal of Immunology. 1969, 103.6 : 1405-1410.

3. Moks, Tomas, et al. Staphylococcal protein A consists of five IgG‐binding domains. European journal of biochemistry. 1986, 156.3:637-643.

4. Goding JW. Use of staphylococcal protein A as an immunological reagent. Journal of immunological methods. 1978, 20:241-53.