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Ran (protein)
Ran (RAs-related Nuclear protein) also known as GTP-binding nuclear protein Ran is a protein that in humans is encoded by the RAN gene. Ran is a small 25 kDa protein that is involved in transport into and out of the cell nucleus during interphase and also involved in mitosis. It is a member of the Ras superfamily. Ran is a small G protein that is essential for the translocation of RNA and proteins through the nuclear pore complex. The Ran protein has also been implicated in the control of DNA synthesis and cell cycle progression, as mutations in Ran have been found to disrupt DNA synthesis. Function Ran cycle Ran exists in the cell in two nucleotide-bound forms: GDP-bound and GTP-bound. RanGDP is converted into RanGTP through the action of RCC1, the nucleotide exchange factor for Ran. RCC1 is also known as RanGEF (Ran Guanine nucleotide Exchange Factor). Ran's intrinsic GTPase-activity is activated through interaction with Ran GTPase activating protein (RanGAP), facilita ... [...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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytoplasmic
In cell biology, the cytoplasm is all of the material within a eukaryotic cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. The main components of the cytoplasm are cytosol (a gel-like substance), the organelles (the cell's internal sub-structures), and various cytoplasmic inclusions. The cytoplasm is about 80% water and is usually colorless. The submicroscopic ground cell substance or cytoplasmic matrix which remains after exclusion of the cell organelles and particles is groundplasm. It is the hyaloplasm of light microscopy, a highly complex, polyphasic system in which all resolvable cytoplasmic elements are suspended, including the larger organelles such as the ribosomes, mitochondria, the plant plastids, lipid droplets, and vacuoles. Most cellular activities take place within the cytoplasm, such as many metabolic pathways including glycolysis, and processes ... [...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 c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prophase
Prophase () is the first stage of cell division in both mitosis and meiosis. Beginning after interphase, DNA has already been replicated when the cell enters prophase. The main occurrences in prophase are the condensation of the chromatin reticulum and the disappearance of the nucleolus. Staining and microscopy Microscopy can be used to visualize condensed chromosomes as they move through meiosis and mitosis. Various DNA stains are used to treat cells such that condensing chromosomes can be visualized as the move through prophase. The giemsa G-banding technique is commonly used to identify mammalian chromosomes, but utilizing the technology on plant cells was originally difficult due to the high degree of chromosome compaction in plant cells. G-banding was fully realized for plant chromosomes in 1990. During both meiotic and mitotic prophase, giemsa staining can be applied to cells to elicit G-banding in chromosomes. Silver staining, a more modern technology, in con ... [...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] |
Exportin
Karyopherins are proteins involved in transporting molecules between the cytoplasm and the nucleus of a eukaryotic cell. The inside of the nucleus is called the karyoplasm (or nucleoplasm). Generally, karyopherin-mediated transport occurs through nuclear pores which acts as a gateway into and out of the nucleus. Most proteins require karyopherins to traverse the nuclear pore. Karyopherins can act as ''importins'' (i.e. helping proteins get into the nucleus) or ''exportins'' (i.e. helping proteins get out of the nucleus). They belong to the nuclear pore complex family in the transporter classification database (TCDB). Energy for transport is derived from the Ran gradient. Upon stress, several karyopherins stop shuttling between the nucleus and the cytoplasm and are sequestered in stress granules, cytoplasmic aggregates of ribonucleoprotein complexes. Importin beta Importin beta is a variety of karyopherin that facilitates the transport of cargo proteins into the nucleus. Firs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Importin
Importin is a type of karyopherin that transports protein molecules from the cell's cytoplasm to the nucleus. It does so by binding to specific recognition sequences, called nuclear localization sequences (NLS). Importin has two subunits, importin α and importin β. Members of the importin-β family can bind and transport cargo by themselves, or can form heterodimers with importin-α. As part of a heterodimer, importin-β mediates interactions with the pore complex, while importin-α acts as an adaptor protein to bind the nuclear localization signal (NLS) on the cargo. The NLS-Importin α-Importin β trimer dissociates after binding to Ran GTP inside the nucleus, with the two importin proteins being recycled to the cytoplasm for further use. Discovery Importin can exist as either a heterodimer of importin-α/β or as a monomer of Importin-β. Importin-α was first isolated in 1994 by a group includinEnno Hartmann based at the Max Delbrück Center for Molecular Medicine. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Localization Signal
A nuclear localization signal ''or'' sequence (NLS) is an amino acid sequence that 'tags' a protein for import into the cell nucleus by nuclear transport. Typically, this signal consists of one or more short sequences of positively charged lysines or arginines exposed on the protein surface. Different nuclear localized proteins may share the same NLS. An NLS has the opposite function of a nuclear export signal (NES), which targets proteins out of the nucleus. Types Classical These types of NLSs can be further classified as either monopartite or bipartite. The major structural differences between the two are that the two basic amino acid clusters in bipartite NLSs are separated by a relatively short spacer sequence (hence bipartite - 2 parts), while monopartite NLSs are not. The first NLS to be discovered was the sequence PKKKRKV in the SV40 Large T-antigen (a monopartite NLS). The NLS of nucleoplasmin, KR AATKKAGQAKKK, is the prototype of the ubiquitous bipartite signal: two clust ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Karyopherin
Karyopherins are proteins involved in transporting molecules between the cytoplasm and the nucleus of a eukaryotic cell. The inside of the nucleus is called the karyoplasm (or nucleoplasm). Generally, karyopherin-mediated transport occurs through nuclear pores which acts as a gateway into and out of the nucleus. Most proteins require karyopherins to traverse the nuclear pore. Karyopherins can act as ''importins'' (i.e. helping proteins get into the nucleus) or ''exportins'' (i.e. helping proteins get out of the nucleus). They belong to the nuclear pore complex family in the transporter classification database (TCDB). Energy for transport is derived from the Ran gradient. Upon stress, several karyopherins stop shuttling between the nucleus and the cytoplasm and are sequestered in stress granules, cytoplasmic aggregates of ribonucleoprotein complexes. Importin beta Importin beta is a variety of karyopherin that facilitates the transport of cargo proteins into the nucleus. Firs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NUTF2
Nuclear transport factor 2 is a protein that in humans is encoded by the ''NUTF2'' gene. Function The protein encoded by this gene is a cytosolic factor that facilitates protein transport into the nucleus. It interacts with the nuclear pore complex glycoprotein p62. This encoded protein acts at a relative late stage of nuclear protein import, subsequent to the initial docking of nuclear import ligand at the nuclear envelope. It is thought to be part of a multicomponent system of cytosolic factors that assemble at the pore complex during nuclear import. Interactions NUTF2 has been shown to interact with Nucleoporin 62 Nuclear pore glycoprotein p62 is a protein complex associated with the nuclear envelope. The p62 protein remains associated with the nuclear pore complex-lamina fraction. p62 is synthesized as a soluble cytoplasmic precursor of 61 kDa followed by ...{ and RAN. References Further reading * * * * * * * * * * * * External links * * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RANBP2
RAN binding protein 2 (RANBP2) is protein which in humans is encoded by the ''RANBP2'' gene. It is also known as nucleoporin 358 (Nup358) since it is a member nucleoporin family that makes up the nuclear pore complex. RanBP2 has a mass of 358 kDa. Function RAN is a small GTP-binding protein of the RAS superfamily. Ran GTPase is a master regulatory switch, which among other functions, controls the shuttling of proteins between the nuclear and cytoplasm compartments of the cell. Ran GTPase controls a variety of cellular functions through its interactions with other proteins. The ''RanBP2'' gene encodes a very large RAN-binding protein that localizes to cytoplasmic filaments emanating from the nuclear pore complex. RanBP2/Nup358 is a giant scaffold and mosaic cyclophilin-related nucleoporin implicated in controlling selective processes of the Ran-GTPase cycle. RanBP2 is composed of multiple domains. Each domain of RanBP2 selectively and directly interacts with distinct proteins s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
