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Cdc34
''CDC34'' is a gene that in humans encodes the protein Ubiquitin-conjugating enzyme E2 R1. This protein is a member of the ubiquitin-conjugating enzyme family, which catalyzes the covalent attachment of ubiquitin to other proteins. CDC34 was originally discovered by work in baker's yeast as a gene that is essential for the cell cycle. Cdc34 in yeast targets numerous substrates - notably the cyclin-dependent kinase inhibitor Sic1 - for ubiquitin-mediated protein degradation. CDC34 is required for ubiquitin-mediated degradation of cell cycle G1 regulators, and for the initiation of DNA replication. Interactions CDC34 has been shown to interact with CSNK2B, BTRC and CDK9 Cyclin-dependent kinase 9 or CDK9 is a cyclin-dependent kinase associated with P-TEFb. Function The protein encoded by this gene is a member of the cyclin-dependent kinase (CDK) family. CDK family members are highly similar to the gene produc .... References External links * Further reading [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CSNK2B
Casein kinase II subunit beta is a protein that in humans is encoded by the ''CSNK2B'' gene. This gene encodes the beta subunit of casein kinase II, a ubiquitous protein kinase which regulates metabolic pathways, signal transduction, transcription, translation, and replication. The enzyme localizes to the endoplasmic reticulum and the Golgi apparatus. Casein kinase, a ubiquitous, well-conserved protein kinase involved in cell metabolism and differentiation, is characterised by its preference for Serine or Threonine in acidic stretches of amino acids. The enzyme is a tetramer of 2 alpha- and 2 beta-subunits. However, some species (e.g., mammals) possess 2 related forms of the alpha-subunit (alpha and alpha'), while others (e.g., fungi) possess 2 related beta-subunits (beta and beta'). The alpha-subunit is the catalytic unit and contains regions characteristic of serine/threonine protein kinases. The beta-subunit is believed to be regulatory, possessing an N-terminal auto-phospho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ubiquitin-conjugating Enzyme
Ubiquitin-conjugating enzymes, also known as E2 enzymes and more rarely as ''ubiquitin-carrier enzymes'', perform the second step in the ubiquitination reaction that targets a protein for degradation via the proteasome. The ubiquitination process covalently attaches ubiquitin, a short protein of 76 amino acids, to a lysine residue on the target protein. Once a protein has been tagged with one ubiquitin molecule, additional rounds of ubiquitination form a polyubiquitin chain that is recognized by the proteasome's 19S regulatory particle, triggering the ATP-dependent unfolding of the target protein that allows passage into the proteasome's 20S core particle, where proteases degrade the target into short peptide fragments for recycling by the cell. Relationships A ubiquitin-activating enzyme, or E1, first activates the ubiquitin by covalently attaching the molecule to its active site cysteine residue. The activated ubiquitin is then transferred to an E2 cysteine. Once conjugated to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BTRC (gene)
F-box/WD repeat-containing protein 1A (FBXW1A) also known as βTrCP1 or Fbxw1 or hsSlimb or pIkappaBalpha-E3 receptor subunit is a protein that in humans is encoded by the ''BTRC'' (beta-transducin repeat containing) gene. This gene encodes a member of the F-box protein family which is characterized by an approximately 40 residue structural motif, the F-box. The F-box proteins constitute one of the four subunits of ubiquitin protein ligase complex called SCFs ( Skp1-Cul1-F-box protein), which often, but not always, recognize substrates in a phosphorylation-dependent manner. F-box proteins are divided into 3 classes: * Fbxws containing WD40 repeats, * Fbxls containing leucine-rich repeats, * and Fbxos containing either "other" protein–protein interaction modules or no recognizable motifs. The protein encoded by this gene belongs to the Fbxw class as, in addition to an F-box, this protein contains multiple WD40 repeats. This protein is homologous to Xenopus βTrCP, yeast Met30, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene
In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a basic unit of heredity and the molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protein-coding genes and noncoding genes. During gene expression, the DNA is first copied into RNA. The RNA can be directly functional or be the intermediate template for a protein that performs a function. The transmission of genes to an organism's offspring is the basis of the inheritance of phenotypic traits. These genes make up different DNA sequences called genotypes. Genotypes along with environmental and developmental factors determine what the phenotypes will be. Most biological traits are under the influence of polygenes (many different genes) as well as g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and organisms, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in protein folding into a specific 3D structure that determines its activity. A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called peptides. The individual amino acid residues are bonded together by peptide bonds and adjacent amino acid residues. The sequence of amino acid resid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Covalent
A covalent bond is a chemical bond that involves the sharing of electrons to form electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs. The stable balance of attractive and repulsive forces between atoms, when they share electrons, is known as covalent bonding. For many molecules, the sharing of electrons allows each atom to attain the equivalent of a full valence shell, corresponding to a stable electronic configuration. In organic chemistry, covalent bonding is much more common than ionic bonding. Covalent bonding also includes many kinds of interactions, including σ-bonding, π-bonding, metal-to-metal bonding, agostic interactions, bent bonds, three-center two-electron bonds and three-center four-electron bonds. The term ''covalent bond'' dates from 1939. The prefix ''co-'' means ''jointly, associated in action, partnered to a lesser degree, '' etc.; thus a "co-valent bond", in essence, means that the atoms share "valence", s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baker's Yeast
Baker's yeast is the common name for the strains of yeast commonly used in baking bread and other bakery products, serving as a leavening agent which causes the bread to rise (expand and become lighter and softer) by converting the fermentable sugars present in the dough into carbon dioxide and ethanol. Baker's yeast is of the species ''Saccharomyces cerevisiae'', and is the same species (but a different strain) as the kind commonly used in alcoholic fermentation, which is called brewer's yeast. Baker's yeast is also a single-cell microorganism found on and around the human body. The use of steamed or boiled potatoes, water from potato boiling, or sugar in a bread dough provides food for the growth of yeasts; however, too much sugar will dehydrate them. Yeast growth is inhibited by both salt and sugar, but more so by salt than sugar. Some sources say fats, such as butter and eggs, slow down yeast growth; others say the effect of fat on dough remains unclear, presenting evi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Cycle
The cell cycle, or cell-division cycle, is the series of events that take place in a cell that cause it to divide into two daughter cells. These events include the duplication of its DNA ( DNA replication) and some of its organelles, and subsequently the partitioning of its cytoplasm, chromosomes and other components into two daughter cells in a process called cell division. In cells with nuclei (eukaryotes, i.e., animal, plant, fungal, and protist cells), the cell cycle is divided into two main stages: interphase and the mitotic (M) phase (including mitosis and cytokinesis). During interphase, the cell grows, accumulating nutrients needed for mitosis, and replicates its DNA and some of its organelles. During the mitotic phase, the replicated chromosomes, organelles, and cytoplasm separate into two new daughter cells. To ensure the proper replication of cellular components and division, there are control mechanisms known as cell cycle checkpoints after each of the ke ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclin-dependent Kinase
Cyclin-dependent kinases (CDKs) are the families of protein kinases first discovered for their role in regulating the cell cycle. They are also involved in regulating transcription, mRNA processing, and the differentiation of nerve cells. They are present in all known eukaryotes, and their regulatory function in the cell cycle has been evolutionarily conserved. In fact, yeast cells can proliferate normally when their CDK gene has been replaced with the homologous human gene. CDKs are relatively small proteins, with molecular weights ranging from 34 to 40 kDa, and contain little more than the kinase domain. By definition, a CDK binds a regulatory protein called a cyclin. Without cyclin, CDK has little kinase activity; only the cyclin-CDK complex is an active kinase but its activity can be typically further modulated by phosphorylation and other binding proteins, like p27. CDKs phosphorylate their substrates on serines and threonines, so they are serine-threonine kinases. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sic1
Sic1, a protein, is a stoichiometric inhibitor of Cdk1-Clb ( B-type cyclins) complexes in the budding yeast ''Saccharomyces cerevisiae''. Because B-type cyclin-Cdk1 complexes are the drivers of S-phase initiation, Sic1 prevents premature S-phase entry. Multisite phosphorylation of Sic1 is thought to time Sic1 ubiquitination and destruction, and by extension, the timing of S-phase entry. Cell cycle control In the G1 phase of the cell cycle, Sic1 binds tightly to the Cdc28-Clb complex and inhibits it. Low Cdc28-Clb activity leads to the disassembly of the mitotic spindle, the assembly of the prereplicative complex and initiation of bud formation in yeast. At the START point in the yeast cell cycle, the G1-cyclins Cln3, Cln1 and Cln 2 activate Cdc28. The activated complex will phosphorylate Sic1 at multiple sites which leads to its degradation by the SCF complex. When Sic1 is degraded, the Cdc28-Clb complex is no longer inhibited and the cell can enter the S/M-phase. Thus Sic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ubiquitin
Ubiquitin is a small (8.6 kDa) regulatory protein found in most tissues of eukaryotic organisms, i.e., it is found ''ubiquitously''. It was discovered in 1975 by Gideon Goldstein and further characterized throughout the late 1970s and 1980s. Four genes in the human genome code for ubiquitin: UBB, UBC, UBA52 and RPS27A. The addition of ubiquitin to a substrate protein is called ubiquitylation (or, alternatively, ubiquitination or ubiquitinylation). Ubiquitylation affects proteins in many ways: it can mark them for degradation via the proteasome, alter their cellular location, affect their activity, and promote or prevent protein interactions. Ubiquitylation involves three main steps: activation, conjugation, and ligation, performed by ubiquitin-activating enzymes (E1s), ubiquitin-conjugating enzymes (E2s), and ubiquitin ligases (E3s), respectively. The result of this sequential cascade is to bind ubiquitin to lysine residues on the protein substrate via an isopeptide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Degradation
Proteolysis is the breakdown of proteins into smaller polypeptides or amino acids. Uncatalysed, the hydrolysis of peptide bonds is extremely slow, taking hundreds of years. Proteolysis is typically catalysed by cellular enzymes called proteases, but may also occur by intra-molecular digestion. Proteolysis in organisms serves many purposes; for example, digestive enzymes break down proteins in food to provide amino acids for the organism, while proteolytic processing of a polypeptide chain after its synthesis may be necessary for the production of an active protein. It is also important in the regulation of some physiological and cellular processes including apoptosis, as well as preventing the accumulation of unwanted or misfolded proteins in cells. Consequently, abnormality in the regulation of proteolysis can cause disease. Proteolysis can also be used as an analytical tool for studying proteins in the laboratory, and it may also be used in industry, for example in food pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
