glutamyl

Glutamyl is a biochemical term used to describe a substituent or residue derived from the amino acid glutamate (glutamic acid). In many contexts the linkage is through the gamma-carboxyl group of the glutamate side chain, yielding gamma-glutamyl compounds. The prefix indicates attachment via the gamma carboxyl rather than the alpha carboxyl.

In metabolism, the gamma-glutamyl moiety is central to reactions catalyzed by gamma-glutamyl transferase (GGT). This enzyme transfers the gamma-glutamyl group from glutathione to acceptor molecules, forming gamma-glutamyl amino acids and other derivatives. This chemistry is part of the gamma-glutamyl cycle, related to amino acid transport and glutathione metabolism. Clinically, GGT activity is commonly measured as a liver function indicator.

In proteins, glutamyl groups can be added to existing glutamate residues to form polyglutamylation, a post-translational modification most notably on tubulin. Enzymes of the TTLL family extend side-chain glutamates, creating polyglutamate chains that influence microtubule stability and interactions with motor proteins and other microtubule-associated factors.

The term also appears in naming conventions, such as glutamyl-tRNA in protein synthesis (the glutamate moiety attached to tRNA) and various gamma-glutamyl derivatives like gamma-glutamylglycine. Overall, glutamyl denotes chemistry and biology related to the gamma-carboxyl-linked forms of glutamate.