|
Parvulin
] Parvulin, a 92-amino acid protein discovered in E. coli in 1994,Rahfeld JU, Schierhorn A, Mann KH. (1994). A novel peptidyl-prolyl cis/trans isomerase from Escherichia coli. ''FEBS Lett'' 343:65. is the smallest known protein with prolyl isomerase activity, which catalyzes the ''cis''-''trans'' isomerization of proline peptide bonds. Although parvulin has no homology with larger prolyl isomerases such as cyclophilin and FKBP, it does share structural features with subdomains of other proteins involved in preparing secreted proteins for export from the cell.Balbach J, Schmid FX. (2000). Proline isomerizarion and its catalysis in protein folding. ''In Mechanisms of Protein Folding'' 2nd ed. Ed. RH Pain. ''Frontiers in Molecular Biology'' series. Oxford University Press: Oxford, UK. Although parvulin is as active as the larger prolyl isomerases against a short proline-containing test peptide, it has lower relative activity against biological substrates, possibly because the larger ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Par14
Par14 (eukaryotic homolog of parvulin, EHPF) is a member of the parvulin family of peptidyl-prolyl-cis/trans-isomerases (PPIases) in humans, which possesses prolyl isomerase activity. History In 1999, Par14 was identified by two groups independently. After the discovery of human Pin1 in 1996, Par14 turned out to be the second member of the human parvulin family. In contrast to Pin1, Par14 exhibits minor catalytic activity, shows no preference for phosphorylated substrates and fails to rescue the loss of the Pin1-related parvulin Ess1 in yeast. Par14 orthologs are found in many unicellular eukaryotes and all multicellular organisms. In 2006, a Par14 isoform, denoted Par17, was described, which carries an N-terminal extension of 25 residues and is exclusively expressed in hominids. Expression and localization Par14 originates from transcription of the PIN4 gene on chromosome Xq13.1. The promotor region is TATA-less and located within a CpG island. The protein is primarily active ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Par17
Par17, a member of the parvulin family of peptidyl-prolyl-cis/trans-isomerases (PPIases), is an isoform of parvulin 14 (Par14) and originates from alternative transcription initiation of the Peptidyl-prolyl cis-trans isomerase NIMA-interacting 4, PIN4 gene on chromosome Xq13 in humans. Par17, which carries a 25 residue N-terminal extension, shares the complete successive amino acid sequence with Par14. In contrast to Par14, Par17 is exclusively expressed in Hominidae, as Open reading frame, ORFs were only found within the genomes of orangutans, gorillas, chimpanzees and humans. The N-terminal extension seems to be responsible for the translocation of Par17 to the mitochondrial matrix. Par17 is involved in tubulin and actin polymerization as well as in hepatitis B virus replication.{{cite journal , doi = 10.1128/JVI.01840-18 , title = Parvulin 14 and Parvulin 17 Bind to HBX and cccDNA and Upregulate Hepatitis B Virus Replication from cccDNA to Virion in an HBX-Dependent Manner , ye ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prolyl Isomerase
Prolyl isomerase (also known as peptidylprolyl isomerase or PPIase) is an enzyme () found in both prokaryotes and eukaryotes that interconverts the ''cis'' and ''trans'' isomers of peptide bonds with the amino acid proline. Proline has an unusually conformationally restrained peptide bond due to its cyclic structure with its side chain bonded to its secondary amine nitrogen. Most amino acids have a strong energetic preference for the ''trans'' peptide bond conformation due to steric hindrance, but proline's unusual structure stabilizes the ''cis'' form so that both isomers are populated under biologically relevant conditions. Proteins with prolyl isomerase activity include cyclophilin, FKBPs, and parvulin, although larger proteins can also contain prolyl isomerase structural domain, domains. Protein folding Proline is unique among the natural amino acids in having a relatively small difference in free energy between the ''cis'' configuration of its peptide bond and the more c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autocatalytic
A single chemical reaction is said to be autocatalytic if one of the reaction products is also a catalyst for the same or a coupled reaction.Steinfeld J.I., Francisco J.S. and Hase W.L. ''Chemical Kinetics and Dynamics'' (2nd ed., Prentice-Hall 1999) p.151-2 Such a reaction is called an autocatalytic reaction. A ''set'' of chemical reactions can be said to be "collectively autocatalytic" if a number of those reactions produce, as reaction products, catalysts for enough of the other reactions that the entire set of chemical reactions is self-sustaining given an input of energy and food molecules (see autocatalytic set). Chemical reactions A chemical reaction of two reactants and two products can be written as : \alpha A + \beta B \rightleftharpoons \sigma S + \tau T where the Greek letters are stoichiometric coefficients and the capital Latin letters represent chemical species. The chemical reaction proceeds in both the forward and reverse direction. This equation is easily g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alzheimer's Disease
Alzheimer's disease (AD) is a neurodegeneration, neurodegenerative disease that usually starts slowly and progressively worsens. It is the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in short-term memory, remembering recent events. As the disease advances, symptoms can include primary progressive aphasia, problems with language, Orientation (mental), disorientation (including easily getting lost), mood swings, loss of motivation, self-neglect, and challenging behaviour, behavioral issues. As a person's condition declines, they often withdraw from family and society. Gradually, bodily functions are lost, ultimately leading to death. Although the speed of progression can vary, the typical life expectancy following diagnosis is three to nine years. The cause of Alzheimer's disease is poorly understood. There are many environmental and genetic risk factors associated with its development. The strongest genetic risk factor is from an alle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amyloid Beta
Amyloid beta (Aβ or Abeta) denotes peptides of 36–43 amino acids that are the main component of the amyloid plaques found in the brains of people with Alzheimer's disease. The peptides derive from the amyloid precursor protein (APP), which is cleaved by beta secretase and gamma secretase to yield Aβ in a cholesterol-dependent process and substrate presentation. Aβ molecules can aggregate to form flexible soluble oligomers which may exist in several forms. It is now believed that certain misfolded oligomers (known as "seeds") can induce other Aβ molecules to also take the misfolded oligomeric form, leading to a chain reaction akin to a prion infection. The oligomers are toxic to nerve cells. The other protein implicated in Alzheimer's disease, tau protein, also forms such prion-like misfolded oligomers, and there is some evidence that misfolded Aβ can induce tau to misfold. A study has suggested that APP and its amyloid potential is of ancient origins, dating as far back a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amyloid Precursor Protein
Amyloid-beta precursor protein (APP) is an integral membrane protein expressed in many biological tissue, tissues and concentrated in the synapses of neurons. It functions as a cell surface receptor and has been implicated as a regulator of synapse formation, neural plasticity, antimicrobial activity, and iron export. It is coded for by the gene ''APP'' and regulated by substrate presentation. APP is best known as the precursor molecule whose proteolysis generates amyloid beta (Aβ), a polypeptide containing 37 to 49 amino acid residues, whose Amyloid#Structure, amyloid fibrillar form is the primary component of amyloid plaques found in the brains of Alzheimer's disease patients. Genetics Amyloid-beta precursor protein is an ancient and highly Conserved sequence, conserved protein. In humans, the gene ''APP'' is located on chromosome 21 and contains 18 exons spanning 290 kilobases. Several alternative splicing isoforms of APP have been observed in humans, ranging in len ... [...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 key steps ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
M Phase
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 key steps of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
G2 Phase
G2 phase, Gap 2 phase, or Growth 2 phase, is the third subphase of interphase in the cell cycle directly preceding mitosis. It follows the successful completion of S phase, during which the cell’s DNA is replicated. G2 phase ends with the onset of prophase, the first phase of mitosis in which the cell’s chromatin condenses into chromosomes. G2 phase is a period of rapid cell growth and protein synthesis during which the cell prepares itself for mitosis. Curiously, G2 phase is not a necessary part of the cell cycle, as some cell types (particularly young ''Xenopus'' embryos and some cancers)) proceed directly from DNA replication to mitosis. Though much is known about the genetic network which regulates G2 phase and subsequent entry into mitosis, there is still much to be discovered concerning its significance and regulation, particularly in regards to cancer. One hypothesis is that the growth in G2 phase is regulated as a method of cell size control. Fission yeast (''Schi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eukaryotic
Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacteria and Archaea (both prokaryotes) make up the other two domains. The eukaryotes are usually now regarded as having emerged in the Archaea or as a sister of the Asgard archaea. This implies that there are only two domains of life, Bacteria and Archaea, with eukaryotes incorporated among archaea. Eukaryotes represent a small minority of the number of organisms, but, due to their generally much larger size, their collective global biomass is estimated to be about equal to that of prokaryotes. Eukaryotes emerged approximately 2.3–1.8 billion years ago, during the Proterozoic eon, likely as flagellated phagotrophs. Their name comes from the Greek εὖ (''eu'', "well" or "good") and κάρυον (''karyon'', "nut" or "kernel"). Euka ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crystal Structure Of Human Parvulin 14
A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macroscopic single crystals are usually identifiable by their geometrical shape, consisting of flat faces with specific, characteristic orientations. The scientific study of crystals and crystal formation is known as crystallography. The process of crystal formation via mechanisms of crystal growth is called crystallization or solidification. The word ''crystal'' derives from the Ancient Greek word (), meaning both "ice" and "rock crystal", from (), "icy cold, frost". Examples of large crystals include snowflakes, diamonds, and table salt. Most inorganic solids are not crystals but polycrystals, i.e. many microscopic crystals fused together into a single solid. Polycrystals include most metals, rocks, ceramics, and ice. A third category of sol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
