Identification of residues mediating homotropic regulation in human hexokinase 3 reveals a common allosteric interface shared with hexokinase 1.

ABSTRACT: Vertebrate hexokinases (HKs) display a variety of allosteric phenomena, including activation and inhibition by both homotropic and heterotropic ligands. The extent to which these homologs share a common allosteric mechanism is unknown. A unique trait of the vertebrate hexokinase 3 (HK3) orthologs is substrate inhibition by glucose. Here, we demonstrate that the isolated, regulatory N-terminal domain of human HK3 contains a low affinity glucose binding site whose dissociation constant (3.2 ± 0.4 mM) approximates the K_i value for glucose (11 ± 2 mM) observed in assays of the full-length enzyme. The isolated, catalytic C-terminal domain harbors a high affinity glucose binding site whose dissociation constant (6.2 ± 0.6 μM) resembles the K_m value for glucose (53 ± 1 μM).

SUBMITTER: Freye C 

PROVIDER: S-EPMC12556919 | biostudies-literature | 2025 Sep

REPOSITORIES: biostudies-literature