Protein G

Alternate Names:

SpG, Streptococcal protein G, Immunoglobulin G-binding protein G, IgG-binding protein G

Overview:

Immunoglobulin (Ig) binding protein, Protein G, is present on the surface of group C and G Streptococcal bacteria. Protein G is known to bind the Fab and Fc regions of the antibody in the host cell and suppresses host cell immune responses (1). Such cross-linking is found to prevent opsonophagocytosis and result in B-cell death in vitro (2). All four human IgG subclasses interact with protein G with high affinity (3). Overall, protein G can be used as an immunological reagent in a broad range of studies that involve detection of antibody-secreting cells (4).

Formulation:

Recombinant protein stored in 50mM sodium phosphate, pH 7.5, 300mM NaCl, 200mM imidazole, 1mM DTT, 10% glycerol.

Storage and Stability:

Store product at -20°C. For optimal storage, aliquot target into smaller quantities after centrifugation and store at recommended temperature. For most favorable performance, avoid repeated handling and multiple freeze/thaw cycles.

Alternative Name(s):

SpG, Streptococcal protein G, Immunoglobulin G-binding protein G, IgG-binding protein G

Scientific Background :

Immunoglobulin (Ig) binding protein, Protein G, is present on the surface of group C and G Streptococcal bacteria. Protein G is known to bind the Fab and Fc regions of the antibody in the host cell and suppresses host cell immune responses (1). Such cross-linking is found to prevent opsonophagocytosis and result in B-cell death in vitro (2). All four human IgG subclasses interact with protein G with high affinity (3). Overall, protein G can be used as an immunological reagent in a broad range of studies that involve detection of antibody-secreting cells (4).

References :

1. Sjobring U, Bjorck L, Kastern W, et al. 1991. Streptococcal protein G. Gene structure and protein binding properties. J Biol Chem. 266 (1): 399-405. 2. Nitsche-Schmitz, D. Patric et al. 2007. Group G Streptococcal IgG Binding Molecules FOG and Protein G Have Different Impacts on Opsonization by C1q. J Biol Chem. 282 (24): 17530 - 17536. 3. Choe W, Durgannavar TA, Chung SJ. 2016. Fc-Binding Ligands of Immunoglobulin G: An Overview of High Affinity Proteins and Peptides. Materials (Basel). 8;9(12):994. 4. Akerström, B, Brodin, T, Reis, K, Björck, L. 1985. Protein G: a powerful tool for binding and detection of monoclonal and polyclonal antibodies. J. Immunology 135(4) 2589-2592.

Molecular weight:

~37 kDa