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DCTN6
In molecular biology, DCTN6 is that subunit of the dynactin protein complex that is encoded by the p27 gene. Dynactin is the essential component for microtubule-based cytoplasmic dynein motor activity in intracellular transport of a variety of cargoes and organelles. Identification and structure DCTN6 was first identified and cloned as a subunit of the "pointed-end complex" of dynactin through biochemical purification. X-ray crystal structure revealed that dynactin p27 forms an unusual left handed β-helix (LβH) domain, and its phosphorylation site T186 is in C-terminal disordered segment. Function In intracellular transport Dynactin p27 forms a hetero-dimer with the other dynactin pointed-end complex subunit p25/DCTN5 in 1:1 ratio, and it is essential for p25 stability since they are co-knockdown by p27 RNAi. However, both p27 and p25 are not required for 19S dynactin complex integrity verified by velocity sedimentation. p27/DCTN6 and other dynactin pointed-end complex sub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dynactin
Dynactin is a 23 Protein subunit, subunit protein complex that acts as a co-factor for the microtubule motor cytoplasmic dynein-1. It is built around a short filament of actin related protein-1 (ACTR1A, Arp1). Discovery Dynactin was identified as an activity that allowed purified cytoplasmic dynein to move membrane vesicles along microtubules in vitro. It was shown to be a multiprotein complex and named "dynactin" because of its role in dynein activation. The main features of dynactin were visualized by quick-freeze, deep-etch, rotary shadow electron microscopy. It appears as a short filament, 37-nm in length, which resembles F-actin, plus a thinner, laterally oriented arm. Antibody labelling was used to map the location of the dynactin subunits. Structure Dynactin consists of three major structural domains: (1) sidearm-shoulder: DCTN1/p150Glued, DCTN2/p50/dynamitin, DCTN3/p24/p22;(2)the Arp1 filament: ACTR1A/Arp1/centractin, actin, CapZ; and (3) the pointed end complex: Acti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mitotic Spindle
In cell biology, the spindle apparatus refers to the cytoskeletal structure of eukaryotic cells that forms during cell division to separate sister chromatids between daughter cells. It is referred to as the mitotic spindle during mitosis, a process that produces genetically identical daughter cells, or the meiotic spindle during meiosis, a process that produces gametes with half the number of chromosomes of the parent cell. Besides chromosomes, the spindle apparatus is composed of hundreds of proteins. Microtubules comprise the most abundant components of the machinery. Spindle structure Attachment of microtubules to chromosomes is mediated by kinetochores, which actively monitor spindle formation and prevent premature anaphase onset. Microtubule polymerization and depolymerization dynamic drive chromosome congression. Depolymerization of microtubules generates tension at kinetochores; bipolar attachment of sister kinetochores to microtubules emanating from opposite cell pol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mad1
Mad1 is a non-essential protein which in yeast has a function in the spindle assembly checkpoint (SAC). This checkpoint monitors chromosome attachment to spindle microtubules and prevents cells from starting anaphase until the spindle is built up. The name Mad refers to the observation that mutant cells are mitotic arrest deficient (MAD) during microtubule depolymerization. Mad1 recruits the anaphase inhibitor Mad2 to unattached kinetochores and is essential for Mad2-Cdc20 complex formation ''in vivo'' but not ''in vitro''. ''In vivo'', Mad1 acts as a competitive inhibitor of the Mad2-Cdc20 complex. Mad1 is phosphorylated by Mps1 which then leads together with other activities to the formation of the mitotic checkpoint complex (MCC). Thereby it inhibits the activity of the anaphase-promoting complex/cyclosome (APC/C). Homologues of Mad1 are conserved in eukaryotes from yeast to mammals. Introduction In the early 90s, yeast genes were identified which mutations resulted in a de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prometaphase
Prometaphase is the phase of mitosis following prophase and preceding metaphase, in eukaryotic somatic cells. In prometaphase, the nuclear membrane breaks apart into numerous "membrane vesicles", and the chromosomes inside form protein structures called kinetochores. Kinetochore microtubules emerging from the centrosomes at the poles (ends) of the spindle reach the chromosomes and attach to the kinetochores, throwing the chromosomes into agitated motion. Other spindle microtubules make contact with microtubules coming from the opposite pole. Forces exerted by protein "motors" associated with spindle microtubules move the chromosomes toward the centre of the cell. Prometaphase is not always presented as a distinct part of mitosis. In sources that do not use the term, the events described here are instead assigned to late prophase and early metaphase. Types of microtubules The microtubules are composed of two types, ''kinetochore microtubules'' and ''non-kinetochore microtu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plk1
Serine/threonine-protein kinase PLK1, also known as polo-like kinase 1 (PLK-1) or serine/threonine-protein kinase 13 (STPK13), is an enzyme that in humans is encoded by the ''PLK1'' (polo-like kinase 1) gene. Structure PLK1 consists of 603 amino acids and is 66kDa. In addition to the N-terminus kinase domain, there are two conserved polo-box regions of 30 amino acids at the C-terminus. Kinase activity is regulated at least in part, by the polo-boxes that are functionally important for both auto-inhibition and subcellular localization. Localization During interphase, PLK1 localizes to centrosomes. In early mitosis, it associates with mitotic spindle poles. A recombinant GFP-PLK1 protein localizes to centromere/kinetochore region, suggesting a possible role for chromosome separation. Cell cycle regulation Plk1 is an early trigger for G2/M transition. Plk1 supports the functional maturation of the centrosome in late G2/early prophase and establishment of the bipolar spindl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polo-like Kinase 1
Serine/threonine-protein kinase PLK1, also known as polo-like kinase 1 (PLK-1) or serine/threonine-protein kinase 13 (STPK13), is an enzyme that in humans is encoded by the ''PLK1'' (polo-like kinase 1) gene. Structure PLK1 consists of 603 amino acids and is 66kDa. In addition to the N-terminus kinase domain, there are two conserved polo-box regions of 30 amino acids at the C-terminus. Kinase activity is regulated at least in part, by the polo-boxes that are functionally important for both auto-inhibition and subcellular localization. Localization During interphase, PLK1 localizes to centrosomes. In early mitosis, it associates with mitotic spindle poles. A recombinant GFP-PLK1 protein localizes to centromere/kinetochore region, suggesting a possible role for chromosome separation. Cell cycle regulation Plk1 is an early trigger for G2/M transition. Plk1 supports the functional maturation of the centrosome in late G2/early prophase and establishment of the bipolar s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cdk1
Cyclin-dependent kinase 1 also known as CDK1 or cell division cycle protein 2 homolog is a highly conserved protein that functions as a serine/threonine protein kinase, and is a key player in cell cycle regulation. It has been highly studied in the budding yeast ''S. cerevisiae'', and the fission yeast ''S. pombe'', where it is encoded by genes ''cdc28'' an''cdc2'' respectively. With its cyclin partners, Cdk1 forms complexes that phosphorylate a variety of target substrates (over 75 have been identified in budding yeast); phosphorylation of these proteins leads to cell cycle progression. Structure Cdk1 is a small protein (approximately 34 kilodaltons), and is highly conserved. The human homolog of Cdk1, ''CDK1'', shares approximately 63% amino-acid identity with its yeast homolog. Furthermore, human ''CDK1'' is capable of rescuing fission yeast carrying a ''cdc2'' mutation. Cdk1 is comprised mostly by the bare protein kinase motif, which other protein kinases share. Cdk1, li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclin-dependent Kinase 1
Cyclin-dependent kinase 1 also known as CDK1 or cell division cycle protein 2 homolog is a highly conserved protein that functions as a serine/threonine protein kinase, and is a key player in cell cycle regulation. It has been highly studied in the budding yeast ''S. cerevisiae'', and the fission yeast ''S. pombe'', where it is encoded by genes ''cdc28'' an''cdc2'' respectively. With its cyclin partners, Cdk1 forms complexes that phosphorylate a variety of target substrates (over 75 have been identified in budding yeast); phosphorylation of these proteins leads to cell cycle progression. Structure Cdk1 is a small protein (approximately 34 kilodaltons), and is highly conserved. The human homolog of Cdk1, ''CDK1'', shares approximately 63% amino-acid identity with its yeast homolog. Furthermore, human ''CDK1'' is capable of rescuing fission yeast carrying a ''cdc2'' mutation. Cdk1 is comprised mostly by the bare protein kinase motif, which other protein kinases share. Cdk1, li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosome
A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are the histones. These proteins, aided by chaperone proteins, bind to and condense the DNA molecule to maintain its integrity. These chromosomes display a complex three-dimensional structure, which plays a significant role in transcriptional regulation. Chromosomes are normally visible under a light microscope only during the metaphase of cell division (where all chromosomes are aligned in the center of the cell in their condensed form). Before this happens, each chromosome is duplicated ( S phase), and both copies are joined by a centromere, resulting either in an X-shaped structure (pictured above), if the centromere is located equatorially, or a two-arm structure, if the centromere is located distally. The joined copies are now called si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kinetochore
A kinetochore (, ) is a disc-shaped protein structure associated with duplicated chromatids in eukaryotic cells where the spindle fibers attach during cell division to pull sister chromatids apart. The kinetochore assembles on the centromere and links the chromosome to microtubule polymers from the mitotic spindle during mitosis and meiosis. The term kinetochore was first used in a footnote in a 1934 Cytology book by Lester W. Sharp and commonly accepted in 1936. Sharp's footnote reads: "The convenient term ''kinetochore'' (= movement place) has been suggested to the author by J. A. Moore", likely referring to John Alexander Moore who had joined Columbia University as a freshman in 1932. Monocentric organisms, including vertebrates, fungi, and most plants, have a single centromeric region on each chromosome which assembles a single, localized kinetochore. Holocentric organisms, such as nematodes and some plants, assemble a kinetochore along the entire length of a chromosome. Ki ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mitosis
In cell biology, mitosis () is a part of the cell cycle in which replicated chromosomes are separated into two new nuclei. Cell division by mitosis gives rise to genetically identical cells in which the total number of chromosomes is maintained. Therefore, mitosis is also known as equational division. In general, mitosis is preceded by S phase of interphase (during which DNA replication occurs) and is often followed by telophase and cytokinesis; which divides the cytoplasm, organelles and cell membrane of one cell into two new cells containing roughly equal shares of these cellular components. The different stages of mitosis altogether define the mitotic (M) phase of an animal cell cycle—the division of the mother cell into two daughter cells genetically identical to each other. The process of mitosis is divided into stages corresponding to the completion of one set of activities and the start of the next. These stages are preprophase (specific to plant cells), prophase ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
P27 (gene)
Cyclin-dependent kinase inhibitor 1B (p27Kip1) is an enzyme inhibitor that in humans is encoded by the CDKN1B gene. It encodes a protein which belongs to the ''Cip/Kip'' family of cyclin dependent kinase (Cdk) inhibitor proteins. The encoded protein binds to and prevents the activation of cyclin E-CDK2 or cyclin D-CDK4 complexes, and thus controls the cell cycle progression at G1. It is often referred to as a cell cycle inhibitor protein because its major function is to stop or slow down the cell division cycle. Function The p27Kip1 gene has a DNA sequence similar to other members of the "Cip/Kip" family which include the p21Cip1/Waf1 and p57Kip2 genes. In addition to this structural similarity the "Cip/Kip" proteins share the functional characteristic of being able to bind several different classes of Cyclin and Cdk molecules. For example, p27Kip1 binds to cyclin D either alone, or when complexed to its catalytic subunit CDK4. In doing so p27Kip1 inhibits the catalytic activ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
