In molecular biology, the GA module, or protein G-related albumin-binding module, is a protein domain which occurs on the surface of numerous Gram-positive bacterial pathogens.

Protein G of group C and G Streptococci interacts with the constant region of IgG and with human serum albumin.

The GA module is composed of a left-handed three-helix bundle and is found in a range of bacterial cell surface proteins.

[1][2] GA modules may promote bacterial growth and virulence in mammalian hosts by scavenging albumin-bound nutrients and camouflaging the bacteria.

[3] Proteins containing a GA module include PAB from Peptostreptococcus magnus.