title: Stanniocalcin 1 binds hemin through a partially conserved heme regulatory motif.
abstract: Hemin (iron protoporphyrin IX) is a necessary component of many proteins, functioning either as a cofactor or an intracellular messenger. Hemoproteins have diverse functions, such as transportation of gases, gas detection, chemical catalysis and electron transfer. Stanniocalcin 1 (STC1) is a protein involved in respiratory responses of the cell but whose mechanism of action is still undetermined. We examined the ability of STC1 to bind hemin in both its reduced and oxidized states and located Cys(114) as the axial ligand of the central iron atom of hemin. The amino acid sequence differs from the established (Cys-Pro) heme regulatory motif (HRM) and therefore presents a novel heme binding motif (Cys-Ser). A STC1 peptide containing the heme binding sequence was able to inhibit both spontaneous and H(2)O(2) induced decay of hemin. Binding of hemin does not affect the mitochondrial localization of STC1.
authors.affiliation: Department of Pathology, Haartman Institute, University of Helsinki and HUSLAB, PO Box 21, Haartmaninkatu 3, FI-00014 Helsinki, Finland. johan.westberg@helsinki.fi
authors.forename: Johan A
authors.initials: JA
authors.lastname: Westberg
authors.forename: Ji
authors.initials: J
authors.lastname: Jiang
authors.forename: Leif C
authors.initials: LC
authors.lastname: Andersson
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D017124:Conserved Sequence; D006023:Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006427:Hemin / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D051379:Mice; D017354:Point Mutation; D011485:Protein Binding; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D006023:Glycoproteins; D011994:Recombinant Proteins; D006427:Hemin; C051795:teleocalcin