title: Novel membrane target proteins for lipoxygenase-derived mono(S)hydroxy fatty acids.
abstract: Hydroxyeicosatetraenoic acids (HETEs) and hydroxyoctadecadienoic acids (HODEs) are major bioactive lipids formed via the lipoxygenase oxygenation of arachidonic and linoleic acid, respectively. These metabolites appear to be involved in various cellular actions including cell proliferation, migration and regulation of enzyme activities such as phospholipases and kinases. In view of the diversity of biological effects of these hydroxy fatty acids, it seems likely that multiple mechanisms are involved. Previous reports showed that 15(S)-HETE inhibited the 5-lipoxygenase in rat basophilic leukemia (RBL-1) cell homogenates and established the presence of specific cellular HETE binding sites in these and other cells. The present study used 15(S)-HETE biotin hydrazide and 15(S)-HETE biotin pentyl amide as probes to identify membrane target proteins present in RBL-1 cells that specifically interact with HETEs and HODEs. Two membrane-associated proteins, with apparent molecular weights of 43 and 58 kDa, were identified that specifically interact with these probes and competition experiments indicated that 13(S)-HODE and 15(S)-HETE were the most effective competitors for the hydrazide probe, followed in decreasing effectiveness by 5(S)-HETE, arachidonic acid, 15(R)-HETE, stearic acid and 12(S)-HHT, a cyclooxygenase product. The two proteins were isolated and microsequencing analysis established their identities as actin and the alpha-subunit of mitochondrial ATP synthase, respectively. In vitro binding studies confirmed that purified actin is a potential 15-HETE binding protein. Subcellular cytosolic fractions exhibited fewer protein-probe complexes than membrane fractions. The association of HETEs and HODEs with these cytoskeletal and mitochondrial proteins, respectively, represents a new development in the potential actions of these hydroxy fatty acids.
authors.affiliation: Department of Biochemistry and Molecular Biology, The George Washington University Medical Center, 2300 Eye Street, NW, Washington, DC 20037, USA.
authors.forename: L T
authors.initials: LT
authors.lastname: Kang
authors.forename: T M
authors.initials: TM
authors.lastname: Phillips
authors.forename: J Y
authors.initials: JY
authors.lastname: Vanderhoek
mesh_terms: D000199:Actins / Q000737:chemistry; D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D001710:Biotin / Q000031:analogs & derivatives / Q000737:chemistry; D015153:Blotting, Western; D002460:Cell Line; D004591:Electrophoresis, Polyacrylamide Gel; D006893:Hydroxyeicosatetraenoic Acids / Q000737:chemistry*; D008084:Lipoxygenase / Q000737:chemistry*; D008163:Luminescent Measurements; D008565:Membrane Proteins / Q000737:chemistry* / Q000302:isolation & purification; D015335:Molecular Probes / Q000737:chemistry; D008969:Molecular Sequence Data; D006180:Proton-Translocating ATPases / Q000737:chemistry; D051381:Rats; D013347:Subcellular Fractions / Q000737:chemistry*; D014316:Tritium
chemical_list: D000199:Actins; D006893:Hydroxyeicosatetraenoic Acids; D008565:Membrane Proteins; D015335:Molecular Probes; D014316:Tritium; C053311:biotin hydrazide; D001710:Biotin; C025984:15-hydroxy-5,8,11,13-eicosatetraenoic acid; D008084:Lipoxygenase; D006180:Proton-Translocating ATPases