This enzyme belongs to the family of
ligases, to be specific those forming carbon-nitrogen bonds as acid-D-amino-acid ligases (peptide synthases). The
systematic name of this enzyme class is 5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxylate:L-aspartate ligase (ADP-forming). This enzyme participates in
purine metabolism.
This particular protein family is of huge importance as it is found in all three
domains of life. It is the seventh step in the pathway of
purine biosynthesis. Purines are vital to all cells as they are involved in energy
metabolism and
DNA synthesis.[1] Furthermore, they are of specific interest to scientific researchers as the study of the purine biosynthesis pathway could lead to the development of
chemotherapeutic drugs.[2] This is because most
cancers lack a salvage pathway for adenine nucleotides and rely entirely on the SAICAR pathway.[3]
Protein domain
This protein domain is found in
eukaryotes,
bacteria and
archaea. It is vital for living organisms since it catalyses a step in the purine biosynthesis pathway which aids energy
metabolism and
DNA synthesis.
Protein domain function
In bacteria and plants this protein domain only catalyses the synthesis of SAICAR. However, in mammals it also catalyses phosphoribosylaminoimidazole carboxylase (AIRC) activity.[3]
Protein domain structure
This particular protein is an octamer made up of 8 identical subunits. Each monomer consists of a central domain and a C-terminal
alpha helix. The central domain consists
of a five-stranded parallel
beta sheet flanked by three alpha helices
one side of the sheet and two alpha helices on the other, forming a three-layer (alpha beta alpha) sandwich.[4]