Glucose-1-phosphate adenylyltransferase, C-terminal Left-handed parallel beta helix (LbH) domain: Glucose-1-phosphate adenylyltransferase is also known as ADP-glucose synthase or ADP-glucose pyrophosphorylase. It catalyzes the first committed and rate-limiting step in starch biosynthesis in plants and glycogen biosynthesis in bacteria. It is the enzymatic site for regulation of storage polysaccharide accumulation in plants and bacteria. The enzyme is a homotetramer, with each subunit containing an N-terminal catalytic domain that resembles a dinucleotide-binding Rossmann fold and a C-terminal LbH fold domain with at 5 turns, each containing three imperfect tandem repeats of a hexapeptide repeat motif (X-[STAV]-X-[LIV]-[GAED]-X). The LbH domain is involved in cooperative allosteric regulation and oligomerization.
Comment:Glc-1-phosphate adenylyltransferase or ADP-Glc pyrophosphorylase forms a homotetramer (a dimer of homodimers). One dimer interface is made almost exclusively by end-to-end stacking between the C-terminal LbH domains of two monomers. The dimer of dimers interface is formed by contacts between N-terminal Rossmann fold domains.
Structure:1YP4_CD; Interface between monomers in Solanum tuberosum ADP-Glc pyrophosphorylase homodimer; defined at 3.5A contacts. - View structure with Cn3D