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Cytochrome B
Cytochrome b within both molecular and cell biology, is a protein found in the mitochondria of eukaryotic cells. It functions as part of the electron transport chain and is the main subunit of transmembrane cytochrome bc1 and b6f complexes. Function In the mitochondrion of eukaryotes and in aerobic prokaryotes, cytochrome b is a component of respiratory chain complex III () — also known as the bc1 complex or ubiquinol-cytochrome c reductase. In plant chloroplasts and cyanobacteria, there is an analogous protein, cytochrome b6, a component of the plastoquinone-plastocyanin reductase (), also known as the b6f complex. These complexes are involved in electron transport, the pumping of protons to create a proton-motive force ( PMF). This proton gradient is used for the generation of ATP. These complexes play a vital role in cells. Structure Cytochrome b/b6 is an integral membrane protein of approximately 400 amino acid residues that probably has 8 transmembrane segments. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytochrome Bc1 Complex
Cytochromes are redox-active proteins containing a heme, with a central Fe atom at its core, as a cofactor. They are involved in electron transport chain and redox catalysis. They are classified according to the type of heme and its mode of binding. Four varieties are recognized by the International Union of Biochemistry and Molecular Biology (IUBMB), cytochromes a, cytochromes b, cytochromes c and cytochrome d. Cytochrome function is linked to the reversible redox change from ferrous (Fe(II)) to the ferric (Fe(III)) oxidation state of the iron found in the heme core. In addition to the classification by the IUBMB into four cytochrome classes, several additional classifications such as cytochrome o and cytochrome P450 can be found in biochemical literature. History Cytochromes were initially described in 1884 by Charles Alexander MacMunn as respiratory pigments (myohematin or histohematin). In the 1920s, Keilin rediscovered these respiratory pigments and named them ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transmembrane Segment
A transmembrane domain (TMD) is a membrane-spanning protein domain. TMDs generally adopt an alpha helix topological conformation, although some TMDs such as those in porins can adopt a different conformation. Because the interior of the lipid bilayer is hydrophobic, the amino acid residues in TMDs are often hydrophobic, although proteins such as membrane pumps and ion channels can contain polar residues. TMDs vary greatly in length, sequence, and hydrophobicity, adopting organelle-specific properties. Functions of transmembrane domains Transmembrane domains are known to perform a variety of functions. These include: * Anchoring transmembrane proteins to the membrane. *Facilitating molecular transport of molecules such as ions and proteins across biological membranes; usually hydrophilic residues and binding sites in the TMDs help in this process. *Signal transduction across the membrane; many transmembrane proteins, such as G protein-coupled receptors, receive extracellular ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MT-CYB
Cytochrome b is a protein that in humans is encoded by the ''MT-CYB'' gene. Its gene product is a subunit of the respiratory chain protein ubiquinol–cytochrome ''c'' reductase (UQCR, complex III or cytochrome ''bc''1 complex), which consists of the products of one mitochondrially encoded gene, ''MT-CYB'' (mitochondrial cytochrome b), and ten nuclear genes—''UQCRC1'', ''UQCRC2'', ''CYC1'', '' UQCRFS1'' (Rieske protein), '' UQCRB'', "11kDa protein", ''UQCRH'' (cyt c1 Hinge protein), Rieske protein presequence, "cyt c1 associated protein", and Rieske-associated protein. Structure The ''MT-CYB'' gene is located on the p arm of mitochondrial DNA in position 12 and spans 1,140 base pairs. The gene produces a 42.7 kDa protein named cytochrome b composed of 380 amino acids. Cytochrome b is an integral membrane protein with hydrophobic properties. The catalytic core of the enzyme is composed of eight transmembrane helices, the iron-sulfur protein, and cytochrome c1. Cytochro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CYB5B
Cytochrome b is a protein that in humans is encoded by the ''MT-CYB'' gene. Its gene product is a subunit of the respiratory chain protein ubiquinol–cytochrome ''c'' reductase (UQCR, complex III or cytochrome ''bc''1 complex), which consists of the products of one mitochondrially encoded gene, ''MT-CYB'' (mitochondrial cytochrome b), and ten nuclear genes—''UQCRC1'', ''UQCRC2'', ''CYC1'', ''UQCRFS1'' (Rieske protein), ''UQCRB'', "11kDa protein", ''UQCRH'' (cyt c1 Hinge protein), Rieske protein presequence, "cyt c1 associated protein", and Rieske-associated protein. Structure The ''MT-CYB'' gene is located on the p arm of mitochondrial DNA in position 12 and spans 1,140 base pairs. The gene produces a 42.7 kDa protein named cytochrome b composed of 380 amino acids. Cytochrome b is an integral membrane protein with hydrophobic properties. The catalytic core of the enzyme is composed of eight transmembrane helices, the iron-sulfur protein, and cytochrome c1. Cytochrome b is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CYB5A
Cytochrome b5, form A (gene name CYB5A), is a human microsomal cytochrome b5. Cytochrome b5 is a membrane bound hemoprotein which functions as an electron carrier for several membrane bound oxygenases. It has two isoforms produced by alternative splicing. Isoform 1 is bound to the cytoplasmic side of the endoplasmic reticulum. It has a C-terminal transmembrane alpha-helix. Isoform 2 was found in cytoplasm. Defects in CYB5A are the cause of type IV hereditary methemoglobinemia Methemoglobinemia, or methaemoglobinaemia, is a condition of elevated methemoglobin in the blood. Symptoms may include headache, dizziness, shortness of breath, nausea, poor muscle coordination, and blue-colored skin (cyanosis). Complications .... References Further reading * * * * * * * * * * * * * * * * * * * * Transmembrane proteins {{membrane-protein-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atovaquone
Atovaquone, sold under the brand name Mepron, is an antimicrobial medication for the prevention and treatment of ''Pneumocystis jirovecii'' pneumonia (PCP). Atovaquone is a chemical compound that belongs to the class of naphthoquinones. Atovaquone is a hydroxy-1,4-naphthoquinone, an analog of both ubiquinone and lawsone, with antipneumocystic activity. Medical uses Atovaquone is a medication used to treat or prevent: * For pneumocystis pneumonia (PCP), it is used in mild cases, although it is not approved for treatment of severe cases. * For toxoplasmosis, the medication has antiparasitic and therapeutic effects. * For malaria, it is one of the two components (along with proguanil) in the drug Malarone. Malarone has fewer side effects and is more expensive than mefloquine. Resistance has been observed. * For babesia, it is often used in conjunction with oral azithromycin. Trimethoprim/sulfamethoxazole (TMP-SMX, Bactrim) is generally considered first-line therapy for PCP ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exercise Intolerance
Exercise intolerance is a condition of inability or decreased ability to perform physical exercise at the normally expected level or duration for people of that age, size, sex, and muscle mass. It also includes experiences of unusually severe post-exercise pain, fatigue, nausea, vomiting or other negative effects. Exercise intolerance is not a disease or syndrome in and of itself, but can result from various disorders. In most cases, the specific reason that exercise is not tolerated is of considerable significance when trying to isolate the cause down to a specific disease. Dysfunctions involving the pulmonary, cardiovascular or neuromuscular systems have been frequently found to be associated with exercise intolerance, with behavioural causes also playing a part. Signs and symptoms Exercise in this context means physical activity, not specifically exercise in a fitness program. For example, a person with exercise intolerance after a heart attack may not be able to susta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus. :E.g. ''Panthera leo'' (lion) and ''Panthera onca'' (jaguar) are two species within the genus '' Panthera''. ''Panthera'' is a genus within the family Felidae. The composition of a genus is determined by taxonomists. The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful: # monophyly – all descendants of an ancestral taxon are grouped together (i.e. phylogenetic analysis should clea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Family (biology)
Family ( la, familia, plural ') is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between order and genus. A family may be divided into subfamilies, which are intermediate ranks between the ranks of family and genus. The official family names are Latin in origin; however, popular names are often used: for example, walnut trees and hickory trees belong to the family Juglandaceae, but that family is commonly referred to as the "walnut family". What belongs to a family—or if a described family should be recognized at all—are proposed and determined by practicing taxonomists. There are no hard rules for describing or recognizing a family, but in plants, they can be characterized on the basis of both vegetative and reproductive features of plant species. Taxonomists often take different positions about descriptions, and there may be no broad consensus across the scientific community for some time. The publishing of new data and opi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phylogenetic
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups of organisms. These relationships are determined by Computational phylogenetics, phylogenetic inference methods that focus on observed heritable traits, such as DNA sequences, protein amino acid sequences, or morphology. The result of such an analysis is a phylogenetic tree—a diagram containing a hypothesis of relationships that reflects the evolutionary history of a group of organisms. The tips of a phylogenetic tree can be living taxa or fossils, and represent the "end" or the present time in an evolutionary lineage. A phylogenetic diagram can be rooted or unrooted. A rooted tree diagram indicates the hypothetical common ancestor of the tree. An unrooted tree diagram (a network) makes no assumption about the ancestral line, and do ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mitochondrial DNA
Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial DNA is only a small portion of the DNA in a eukaryotic cell; most of the DNA can be found in the cell nucleus and, in plants and algae, also in plastids such as chloroplasts. Human mitochondrial DNA was the first significant part of the human genome to be sequenced. This sequencing revealed that the human mtDNA includes 16,569 base pairs and encodes 13 proteins. Since animal mtDNA evolves faster than nuclear genetic markers, it represents a mainstay of phylogenetics and evolutionary biology. It also permits an examination of the relatedness of populations, and so has become important in anthropology and biogeography. Origin Nuclear and mitochondrial DNA are thought to be of separate evolutionary origin, with the mtDNA being derive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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