title: A membrane-bound vertebrate globin.
abstract: The family of vertebrate globins includes hemoglobin, myoglobin, and other O(2)-binding proteins of yet unclear functions. Among these, globin X is restricted to fish and amphibians. Zebrafish (Danio rerio) globin X is expressed at low levels in neurons of the central nervous system and appears to be associated with the sensory system. The protein harbors a unique N-terminal extension with putative N-myristoylation and S-palmitoylation sites, suggesting membrane-association. Intracellular localization and transport of globin X was studied in 3T3 cells employing green fluorescence protein fusion constructs. Both myristoylation and palmitoylation sites are required for correct targeting and membrane localization of globin X. To the best of our knowledge, this is the first time that a vertebrate globin has been identified as component of the cell membrane. Globin X has a hexacoordinate binding scheme and displays cooperative O(2) binding with a variable affinity (P(50)∼1.3-12.5 torr), depending on buffer conditions. A respiratory function of globin X is unlikely, but analogous to some prokaryotic membrane-globins it may either protect the lipids in cell membrane from oxidation or may act as a redox-sensing or signaling protein.
authors.affiliation: Biocenter Grindel, University of Hamburg, Hamburg, Germany.
authors.forename: Miriam
authors.initials: M
authors.lastname: Blank
authors.forename: Jessica
authors.initials: J
authors.lastname: Wollberg
authors.forename: Frank
authors.initials: F
authors.lastname: Gerlach
authors.forename: Katja
authors.initials: K
authors.lastname: Reimann
authors.forename: Anja
authors.initials: A
authors.lastname: Roesner
authors.forename: Thomas
authors.initials: T
authors.lastname: Hankeln
authors.forename: Angela
authors.initials: A
authors.lastname: Fago
authors.forename: Roy E
authors.initials: RE
authors.lastname: Weber
authors.forename: Thorsten
authors.initials: T
authors.lastname: Burmester
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D005914:Globins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006418:Heme / Q000378:metabolism; D007074:Immunoglobulin G / Q000276:immunology / Q000378:metabolism; D054878:Lipoylation; D008969:Molecular Sequence Data; D010100:Oxygen / Q000378:metabolism*; D011817:Rabbits; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013347:Subcellular Fractions; D015027:Zebrafish / Q000502:physiology*
chemical_list: D007074:Immunoglobulin G; D011994:Recombinant Proteins; D049452:Green Fluorescent Proteins; D006418:Heme; D005914:Globins; D010100:Oxygen