GGH is a 318 amino acid protein that is secreted into the extracellular space and is also localized to both the lysosome and the melanosome. Functioning as a hydrolase, GGH contains one gamma-glutamyl hydrolase domain through which it catalyzes the hydrolysis of polyglutamate sidechains from pteroylpolyglutamates, specifically hydrolyzing gamma-glutamyl bonds. Via its catalytic activity, GGH may play a role in the bioavailability and metabolic activity of pteroylpolyglutamates. Polymorphisms in the gene encoding GGH are associated with rheumatoid arthritis, inflammatory bowel disease and various cancers. The gene encoding GGH maps to human chromosome 8, which consists of nearly 146 million base pairs, houses more than 800 genes and is associated with a variety of diseases and malignancies.