Recombinant protein G is produced in a strain of E. coli which contains the gene for protein G from Streptococcus sp. It is supplied as a salt-free lyophilized powder.

Recombinant protein G binds to the Fc region of many types of immunoglobulin G including:

• all four subclasses of human IgG
• mouse IgG
• rabbit IgG
• guinea pig IgG
• rat IgG
• goat IgG
• sheep IgG
• cow IgG
• horse IgG

Recombinant protein G does not bind to IgG from chicken or cat, or to human IgA, IgM, or serum albumin. It binds weakly to IgG from dog.