nucleotide-binding domain (NBD) of metazoan glycerol kinase 1-3 (GK1-3) and similar proteins
This subfamily contains metazoan glycerol kinases (GKs), coded by X chromosome-linked GK genes, and glycerol kinase (GK)-like proteins, coded by autosomal testis-specific GK-like genes (GK-like genes, GK2 and GK3). Sequence comparison shows that metazoan GKs and GK-like proteins in this family are closely related to the bacterial GKs (EC 2.7.1.30), which catalyze the Mg-ATP dependent phosphorylation of glycerol to yield glycerol 3-phosphate (G3P). The metazoan GKs do have GK enzymatic activity. However, the GK-like metazoan proteins do not exhibit GK activity and their biological functions are not yet clear. Some of them lack important functional residues involved in the binding of ADP and Mg2+, which may result in the loss of GK catalytic function. Others that have conserved catalytic residues have lost their GK activity as well; the reason remains unclear. It has been suggested the conserved catalytic residues might facilitate them performing a distinct function. Members of this subfamily belong to the FGGY family of carbohydrate kinases, the monomers of which contain two large domains, which are separated by a deep cleft that forms the active site. This model includes both the N-terminal domain, which adopts a ribonuclease H-like fold, and the structurally related C-terminal domain.
Comment:catalytic residues (Asp, Thr, Asp) conserved in the FGGY family
Comment:Two Asp residues probably form a metal cofactor binding site and the second Asp residue acts as a catalytic base.
Comment:It has been proposed that the first Asp coordinates and positions the MgATP, and (in concert with the Mg2+) stabilizes the ADP leaving group during the phospho transfer. The second Asp would act as a general base during catalysis, assisting the removal of a proton from the attacking hydroxyl group. The Thr could stabilize the transition state.
Jiyao W et al.(2023). "The conserved domain database in 2023.",