title: Mammalian hexokinase 1: evolutionary conservation and structure to function analysis.
abstract: We have amplified and sequenced the complete coding region of bovine hexokinase isoenzyme 1 (HK1) from brain RNA with PCR primers selected for sequence conservation. The sequence information was analyzed to evaluate the evolutionary and structure-function relationships among the mammalian and yeast HK isoenzymes. Structure to function analysis identified an unduplicated, invariant N-terminal domain involved in HK1 outer mitochondrial membrane targeting, as well as putative carbohydrate and nucleotide-binding sites in the regulatory and catalytic halves of HK1 essential to enzyme function. The ATP-binding site in the catalytic half of the HK1 protein resembles nucleotide-binding regions from protein kinases, with the single amino acid replacement (lysine to glutamate) in the ATP-binding site of the amino half explaining the loss of HK1 catalytic function in the regulatory domain. Sequence comparisons suggest that the 50-kDa mammalian and yeast glucokinases arose separately in evolution. In addition to providing valuable phylogenetic and structure-function insights, this work provides an efficient strategy for rapid cloning and sequencing of the coding regions for other HKs and related proteins.
authors.affiliation: Institute for Molecular Genetics, Baylor College of Medicine, Houston, Texas.
authors.forename: L D
authors.initials: LD
authors.lastname: Griffin
authors.forename: B D
authors.initials: BD
authors.lastname: Gelb
authors.forename: D A
authors.initials: DA
authors.lastname: Wheeler
authors.forename: D
authors.initials: D
authors.lastname: Davison
authors.forename: V
authors.initials: V
authors.lastname: Adams
authors.forename: E R
authors.initials: ER
authors.lastname: McCabe
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D005075:Biological Evolution; D002417:Cattle; D003001:Cloning, Molecular; D006593:Hexokinase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D051381:Rats; D012689:Sequence Homology, Nucleic Acid; D013329:Structure-Activity Relationship
chemical_list: D007527:Isoenzymes; D006593:Hexokinase