A Membrane-Bound Vertebrate Globin

作者：Blank Miriam^*; Wollberg Jessica; Gerlach Frank; Reimann Katja; Roesner Anja; Hankeln Thomas; Fago Angela; Weber Roy E; Burmester Thorsten

来源：PLos One, 2011, 6(9): e25292.

DOI：10.1371/journal.pone.0025292

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)similar to 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 redoxsensing or signaling protein.

• 出版日期2011-9-20