(1E)-ethylideneformamide

Title: Rat Brain Hexokinase Type I Complex With Glucose and Inhibitor Glucose-6-Phosphate
Compound: Mol_Id: 1; Molecule: Hexokinase; Chain: A, B;
Synonym: ATP/: D-Hexose-6-Phosphotransferase; Ec: 2.7.1.1;
Biological_Unit: Monomer
Authors: A. M. Mulichak, R. M. Garavito
Exp. Method: X-ray Diffraction
Classification: Hexokinase
EC Number: 2.7.1.1 (Hexokinase)
Source: Rattus norvegicus
Primary Citation: Mulichak, A. M., Wilson, J. E., Padmanabhan, K.,
Garavito, R. M.: The structure of mammalian hexokinase-1. Nat
Struct Biol 5 pp. 555 (1998)

Description/ Abstract Brain hexokinase (HK) consists of a single polypeptide chain with M/sub r/ approx.^100,000.^Limited proteolysis of native HK with trypsin yields three major fragments, thought to correspond to discrete structural domains, with molecular masses of approximately 10, 50, and 40 kDa, and derived from the N-terminal, central, and C-terminal regions, respectively.^Additional tryptic cleavage sites become susceptible in conformations induced by binding of specific ligands.^A library of monoclonal antibodies has been developed for use as probes in examining the structure and function of domains present in HK.^Epitopes for several of these have been mapped to specific structural regions in HK.^Immunoblotting experiments with these antibodies have been useful in defining the location of susceptible proteolytic cleavage sites in various ligand-induced conformations of HK.^Effects of ligand binding on epitope recognition have indicated that several of the antibodies interact with epitopes perturbed by ligand-induced conformational changes.^Effects of antibody binding on function have also provided a basis for establishing structure-function relationships.^For example, several of the monoclonal antibodies inhibit binding of hexokinase to mitochondria and all recognize epitopes located in the 10 kDa N-terminal domain, consistent with other results indicating that this region is critical to the binding function of hexokinase.