nucleotide-binding domain (NBD) of metazoan glycerol kinase 5 (GK5) and similar proteins
The subfamily corresponds to a group of metazoan putative glycerol kinases (GK), which may be coded by the GK-like gene, GK5. Sequence comparison shows members of this group are homologs of bacterial GKs, and they retain all functionally important residues. However, GK-like proteins in this family do not have detectable GK activity. The reason remains unclear. It has been suggested that the conserved catalytic residues might facilitate them performing a distinct function. GK5 is a skin-specific kinase expressed predominantly in sebaceous glands. It can form a complex with the sterol regulatory element-binding proteins (SREBPs) through their C-terminal regulatory domains, inhibiting SREBP processing and activation. GK5 also promotes gefitinib resistance by inhibiting apoptosis and cell cycle arrest. 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.",