HUMAN HEXOKINASE-II MESSENGER-RNA AND GENE STRUCTURE

This study reports the isolation and characterization of the human hex okinase II (HKII) gene. This gene is similar to 50 kilobases in length and contains 18 exons, ranging in size from 96 to 2,536 base pairs, t hat are exactly the same size as the corresponding exons in the rat HK II gene. A cDNA representing the entire open reading frame for HKII wa s synthesized using a series of polymerase chain reactions with human skeletal muscle RNA as the template, and this allowed us to deduce the complete structure of the HKII mRNA, The human HKII mRNA has 431 nucl eotides (nt) of 5' noncoding sequence, 2,751 nt of coding sequence, an d 2,394 nt of 3' noncoding sequence. The open reading frame encodes a protein of 917 amino acids with an estimated molecular mass of 102.4 k Da. There is a high degree of similarity in the amino acid and nt sequ ences of the rat and human glucokinase and HKII proteins and genes, Th is, coupled with the observation that the exon sizes are conserved, su ggests a common evolutionary origin of the these two genes.