staphylococcal protein a

Staphylococcal protein A is a cell wall-associated protein derived from Staphylococcus aureus. It is a highly conserved bacterial virulence factor with multifunctional immunomodulatory properties. Protein A binds with high affinity to the Fc region of immunoglobulin G (IgG) and also interacts with the Fab region of certain B-cell receptors (VH3 family), thereby interfering with normal antibody function and immune responses[2][3][5]. This binding impairs opsonization and phagocytosis by sequestering antibodies away from their effector functions. Additionally, staphylococcal protein A can bind to other host proteins such as tumor necrosis factor alpha receptor 1 (TNFRSF1A) and von Willebrand factor[3][5]. Recombinant forms are produced in E. coli for research and therapeutic development purposes[2]. As an investigational drug (e.g., PRTX-100), it has been studied for its immunomodulatory effects in autoimmune diseases such as rheumatoid arthritis and idiopathic thrombocytopenic purpura[6].

Other names

Immunoglobulin G-binding protein AIgG-binding protein ASPA