ArticleBiochemistry2007
Axial ligation and stoichiometry of heme centers in adrenal cytochrome b561.
Article in Biochemistry, 2007. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 12 papers.
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Who cites it
12 citing papers in PubMed, 22 citations in OpenAlex.
- Methionine coordination to the heme iron and its displacement by nitric oxide in the CcoP subunit of Pseudomonas aeruginosa cytochrome cbbJournal of inorganic biochemistry · 2026Article
- Cecytb-2, a CytochromeBiomolecules · 2025Article
- Role of the human cytochrome b561 family in iron metabolism and tumors (Review).Oncology letters · 2025Review
- Spectral and Redox Properties of a Recombinant Mouse CytochromeMolecules (Basel, Switzerland) · 2023Article
- Expansion of the Major Facilitator Superfamily (MFS) to include novel transporters as well as transmembrane-acting enzymes.Biochimica et biophysica acta. Biomembranes · 2020Article
- Tuning of Hemes b Equilibrium Redox Potential Is Not Required for Cross-Membrane Electron Transfer.The Journal of biological chemistry · 2016Article
- Cytochromes b561: ascorbate-mediated trans-membrane electron transport.Antioxidants & redox signaling · 2013Review
- High-yield production, purification and characterization of functional human duodenal cytochrome b in an Escherichia coli system.Protein expression and purification · 2011Article
- Functional and structural roles of residues in the third extramembrane segment of adrenal cytochrome b561.Biochemistry · 2011Article
- Spectral characterization of the recombinant mouse tumor suppressor 101F6 protein.European biophysics journal : EBJ · 2010Article
- Auxin-responsive genes AIR12 code for a new family of plasma membrane b-type cytochromes specific to flowering plants.Plant physiology · 2009Article
- His92 and His110 selectively affect different heme centers of adrenal cytochrome b(561).Biochimica et biophysica acta · 2008Article
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Authors and funding
5 authors at 2 institutions in 1 country.
Funding
Abstract
Cytochrome (cyt) b561 transports electrons across the membrane of chromaffin granules (CG) present in the adrenal medulla, supporting the biosynthesis of norepinephrine in the CG matrix. We have conducted a detailed characterization of cyt b561 using electron paramagnetic resonance (EPR) and optical spectroscopy on the wild-type and mutant forms of the cytochrome expressed in insect cells. The gz = 3.7 (low-potential heme) and gz = 3.1 (high-potential heme) signals were found to represent the only two authentic hemes of cyt b561; models that propose smaller or greater amounts of heme can be ruled out. We identified the axial ligands to hemes in cyt b561 by mutating four conserved histidines (His54 and His122 at the matrix-side heme center and His88 and His161 at the cytoplasmic-side heme center), thus confirming earlier structural models. Single mutations of any of these histidines produced a constellation of spectroscopic changes that involve not one but both heme centers. We hypothesize that the two hemes and their axial ligands in cyt b561 are integral parts of a structural unit that we term the "kernel". Histidine to glutamine substitutions in the cytoplasmic-side heme center but not in the matrix-side heme center led to the retention of a small fraction of the low-potential heme with gz = 3.7. We provisionally assign the low-potential heme to the matrix side of the membrane; this arrangement suggests that the membrane potential modulates electron transport across the CG membrane.
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