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The N‐Terminal Atypical Region Regulates Non‐Mitochondrial Localization of Novel Hexokinase Isoform
Author(s) -
Kumar Sujeet,
Parameswaran Sreejit,
Sharma Rajendra
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.728.35
Subject(s) - hexokinase , gene isoform , hek 293 cells , microbiology and biotechnology , myristoylation , subcellular localization , biochemistry , mitochondrion , protein–protein interaction , amino acid , fusion protein , chemistry , voltage dependent anion channel , biology , enzyme , glycolysis , bacterial outer membrane , phosphorylation , gene , recombinant dna , escherichia coli
Post‐translational modifications (PTM) constitute the core dynamic signalling pathways in diverse physiological states. The PTMs render unique functionalization to proteins mediated by specific interactions and are often involved in modular interactions. Hexokinase, the first enzyme in the glucose utilization pathway, is an integral player in modulation of signalling pathways in diverse states. An integral feature of hexokinase functional regulation is binding to VDAC located in the outer‐mitochondrial membrane. The mitochondrial attachment of hexokinase is mediated by 15‐20 amino acid long hydrophobic domain located at N‐terminus of the enzyme.We observe that, in a novel isoform lacking this hydrophobic domain, the membranous interaction is modulated by virtue of PTMs. We cloned the full‐length isoform of hexokinase under CMV promoter in fusion with red fluorescent protein (RFP). Comparisons in parallel were carried out with constructs encoding the normal hexokinase variant fused to green fluorescent protein. The constructs were analyzed for localization by confocal analysis after transfection into HEK293 cells. The localization of these two isoforms showed a clearly distinct behavior. Moreover, the localization of the novel isoform was perturbed when the putative residues involved in the PTMs were mutated to alanine. The PTMs in the atypical region seems to provide an unique functional module. It is imperative to understand the mechanisms of such re‐functionalization in regulation of protein functions. Further insights into the role of myristoylation on the process of ATP generation, if any, and on regulation of glycolytic pathway should improve our understanding of previously un‐described functions.