Intramembrane position of the fluorescent tryptophanyl residue in membrane-bound cytochrome b5

Biochemistry ◽  
1979 ◽  
Vol 18 (24) ◽  
pp. 5458-5464 ◽  
Author(s):  
Patrick J. Fleming ◽  
Dennis E. Koppel ◽  
Arthur L. Y. Lau ◽  
Philipp Strittmatter
Keyword(s):  
Cytochrome B5 ◽  
Membrane Bound ◽  
Tryptophanyl Residue

Fluorescence study of a temperature-induced conversion from the "loose" to the "tight" binding form of membrane-bound cytochrome b5

Biochemistry ◽  
1993 ◽  
Vol 32 (27) ◽  
pp. 6951-6956 ◽  
Author(s):  
Alexey S. Ladokhin ◽  
L. Wang ◽  
A. W. Steggles ◽  
H. Malak ◽  
Peter W. Holloway
Keyword(s):  
Cytochrome B5 ◽  
Tight Binding ◽  
Fluorescence Study ◽  
Membrane Bound

Cytochrome b5 Reductase T116S Mutation and Hemolysis in Sickle Cell Disease.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 903-903 ◽  
Author(s):  
Mehdi Nouraie ◽  
Noel S. Reading ◽  
Andrew Campbell ◽  
Caterina Minniti ◽  
Sohail R Rana ◽  
...  
Keyword(s):  
African Americans ◽  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Tricuspid Regurgitation ◽  
Cytochrome B5 ◽  
Type I ◽  
Systolic Pulmonary Artery Pressure ◽  
Cell Disease ◽  
Cytochrome B5 Reductase ◽  
Membrane Bound

Abstract Abstract 903 Abstract Background: Deficiency of NADH-cytochrome b5 reductase (cytb5r, EC 1.6.2.2) is responsible for congenital methemoglobinemia. This enzyme exists in soluble and membrane-bound forms. The soluble erythrocytic cytb5r isoenzyme is involved in cytochrome b5 reduction and in erythrocyte methemoglobin reduction; the membrane-bound microsomal enzyme participates in a fatty acid desaturation complex and in drug metabolism. The cytb5r isoforms are the product of a single gene locus, DIA1 (or CYB5R3), on chromosome 22. More then 40 mutations which cause methemoglobinemia have been reported to date; the majority are missense mutations and are associated with mild type I methemoglobinemia. The CYBR5 T116S mutation is the most common genetic polymorphism among African Americans known (gene frequency as high as 20%) and it has not yet been detected in other ethnic and racial groups. This polymorphism is not associated with methemoglobinemia and its functional significance is not yet known. We studied the relationship of CYBR5 T116S with the degree of hemolysis and the tricuspid regurgitation velocity (which correlates with systolic pulmonary artery pressure) in patients with sickle cell disease. Methods: Two hundred sixty one children and adolescents with hemoglobin SS were recruited at three tertiary medical centers and studied at steady state. Patients with other sickle genotypes were excluded from this analysis of CYBR5 T116S. Principal component analysis was used to develop a hemolytic component from reticulocyte count and concentrations of lactate dehydrogenase, aspartate aminotransferase and bilirubin. PCR was used to determine the presence of the CYBR5 T116S mutation. Multivariate models were employed to determine the independent effects of this genotype on degree of hemolysis and tricuspid regurgitation velocity. Results: Ninety-eight of the patients (38%) were CYBR5 T116S heterozygotes and 26 (10%) were homozygotes, consistent with Hardy-Weinberg equilibrium. Both heterozygosity (beta = -0.4) and homozygosity (beta = -0.5) were associated with reduction in the hemolytic component (N = 261; P for trend = 0.002) (Figure 1). This relationship persisted after adjusting for α-thalassemia, hemoglobin F percent and hydroxyurea treatment in a subset of 113 patients with all of this information available (P for trend = 0.037) and it also persisted in a subset of 87 patients with no α-globin gene deletion who were not being treated with hydroxyurea (P for trend = 0.029). In none of these analyses did G6PD-202/-376 have an effect on hemolysis. Both heterozygosity (beta = -0.04) and homozygosity (beta = -0.14) for the CYBR5 T116S mutation were also associated with lower tricuspid regurgitation velocity (P for trend = 0.024). Conclusions: CYBR5 T116S is a common polymorphism among patients with sickle cell disease that appears to be associated with less hemolysis and lower tricuspid regurgitation velocity. We speculate that this polymorphism may be related to a previously reported subpopulation of African Americans with increased cytochrome b5 reductase activity, and that increased anti-oxidant activity may explain the polymorphism's hemolysis-reducing effect. Functional studies to investigate this possibility are planned. Disclosures: No relevant conflicts of interest to declare.

Clustering of plasma membrane-bound cytochrome b5 reductase within ‘lipid raft’ microdomains of the neuronal plasma membrane

2009 ◽  
Vol 40 (1) ◽  
pp. 14-26 ◽  
Author(s):  
Alejandro K. Samhan-Arias ◽  
Miguel Angel Garcia-Bereguiain ◽  
Francisco J. Martin-Romero ◽  
Carlos Gutierrez-Merino
Keyword(s):  
Plasma Membrane ◽  
Lipid Raft ◽  
Cytochrome B5 ◽  
Cytochrome B5 Reductase ◽  
Membrane Bound ◽  
Neuronal Plasma Membrane ◽  
Lipid Raft Microdomains

Transcriptional and translational mechanisms of cytochrome b5 reductase isoenzyme generation in humans

2001 ◽  
Vol 355 (2) ◽  
pp. 529-535 ◽  
Author(s):  
Alena LEROUX ◽  
Luisa MOTA VIEIRA ◽  
Axel KAHN
Keyword(s):  
Cytochrome B5 ◽  
Protein Isoforms ◽  
In Vitro Translation ◽  
Alu Elements ◽  
Cytochrome B5 Reductase ◽  
Dynamic Events ◽  
Membrane Bound ◽  
Essential Enzyme ◽  
Translational Mechanisms

Cytochrome b5 reductase (b5R) is an essential enzyme that exists in soluble and membrane-bound isoforms, each with specific functions. In the rat, the two forms are generated from alternative transcripts differing in the first exons. In contrast, the biogenesis of b5R isoforms in the human is not yet well understood. In the present study we have detected three novel alternative exons, designated 1S, S′ and 1B, located between the first alternative exon 1M and the common second exon in the human b5R gene. Accordingly, multiple M-type, S-type and SS′-type and B-type transcripts are generated. All types of human b5R transcript are expressed ubiquitously. An analysis of in vitro translation products demonstrated an alternative use of different AUG initiators resulting in the production of various human b5R protein isoforms. Our results indicate that the organization of the 5′ region of the b5R gene is not conserved between rodents and humans. Insertion of Alu elements into the human b5R gene, in particular just upstream of the S/S′ region, could be responsible for dynamic events of gene rearrangement during evolution.

scholarly journals Molecular and antigenic properties of cytochrome b5 from slow-muscle sarcoplasmic reticulum

1981 ◽  
Vol 197 (2) ◽  
pp. 515-518 ◽  
Author(s):  
G Salviati ◽  
S Salvatori ◽  
R Betto ◽  
A Margreth
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Reductase Activity ◽  
Polyacrylamide Gel Electrophoresis ◽  
Cytochrome B5 ◽  
Slow Muscle ◽  
Molecular Weights ◽  
Antigenic Properties ◽  
Microsomal Cytochrome B5 ◽  
Membrane Bound ◽  
Nadh Cytochrome

NADH-cytochrome b5 reductase and cytochrome b5 associated with slow-muscle sarcoplasmic reticulum and liver microsomal fraction were identified with discrete protein bands of molecular weights 33000 and 16700 by polyacrylamide-gel electrophoresis. Purified detergent-extracted cytochrome b5 from muscle sarcoplasmic reticulum is indistinguishable from liver microsomal cytochrome b5 with respect to spectral properties, pI values and immunological reactivity with antibody to the liver cytochrome b5. Reaction of the antibody with membrane-bound cytochrome b5 inhibits the sarcoplasmic-reticulum NADH-cytochrome c reductase activity.

Human Sterol 14α-Demethylase Activity Is Enhanced by the Membrane-Bound State of Cytochrome b5

2001 ◽  
Vol 395 (1) ◽  
pp. 78-84 ◽  
Author(s):  
David C. Lamb ◽  
Naheed N. Kaderbhai ◽  
K. Venkateswarlu ◽  
Diane E. Kelly ◽  
Steven L. Kelly ◽  
...  
Keyword(s):  
Cytochrome B5 ◽  
Bound State ◽  
Demethylase Activity ◽  
Membrane Bound
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