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Cohesin
Cohesin is a protein complex that mediates Establishment of sister chromatid cohesion, sister chromatid cohesion, homologous recombination, and Topologically associating domain, DNA looping. Cohesin is formed of SMC3, SMC1A, SMC1, RAD21, SCC1 and SCC3 (STAG1, SA1 or STAG2, SA2 in humans). Cohesin holds sister chromatids together after DNA replication until anaphase when removal of cohesin leads to separation of sister chromatids. The complex forms a ring-like structure and it is believed that sister chromatids are held together by entrapment inside the cohesin ring. Cohesin is a member of the SMC proteins, SMC family of protein complexes which includes Condensin, Nucleoid#MukBEF, MukBEF and SMC-ScpAB. Cohesin was separately discovered in budding yeast (''Saccharomyces cerevisiae'') both by Douglas Koshland and Kim Nasmyth in 1997. Structure and subunits Cohesin is a multi-subunit protein complex, made up of SMC1, SMC3, RAD21 and SCC3 (SA1 or SA2). SMC1 and SMC3 are members of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RAD21
Double-strand-break repair protein rad21 homolog is a protein that in humans is encoded by the ''RAD21'' gene. ''RAD21'' (also known as ''Mcd1'', ''Scc1'', ''KIAA0078'', ''NXP1'', ''HR21''), an essential gene, encodes a DNA repair#Double-strand breaks, DNA double-strand break (DSB) repair protein that is evolutionarily conserved in all eukaryotes from budding yeast to humans. RAD21 protein is a structural component of the highly conserved cohesin complex consisting of RAD21, SMC1A, SMC3, and SCC3 [ STAG1 (SA1) and STAG2 (SA2) in multicellular organisms] proteins, involved in Establishment of sister chromatid cohesion, sister chromatid cohesion. Discovery ''rad21'' was first cloned by Birkenbihl and Subramani in 1992 by complementing the radiation sensitivity of the ''rad21-45'' mutant fission yeast, ''Schizosaccharomyces pombe'', and the House mouse, murine and human homologs of ''S. pombe'' rad21 were cloned by McKay, Troelstra, van der Spek, Kanaar, Smit, Hagemeijer, Dirk B ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Loop Extrusion
Loop extrusion is a major mechanism of Nuclear organization. It is a dynamic process in which structural maintenance of chromosomes (SMC) protein complexes progressively grow loops of DNA or chromatin. In this process, SMC complexes, such as condensin or cohesin, bind to DNA/chromatin, use ATP-driven motor activity to reel in DNA, and as a result, extrude the collected DNA as a loop. Background The organization of DNA presents a remarkable biological challenge: human DNA can reach 2 meters and is packed into the nucleus with the diameter of 5-20 μm. At the same time, the critical cell processes involve complex processes on highly compacted DNA, such as transcription, replication, recombination, DNA repair, and cell division. Loop extrusion is a key mechanism that organizes DNA into loops, enabling its efficient compaction and functional organization. For instance, ''in vitro'' experiments show that cohesin can compact DNA by 80%, while condensin achieves a remarkable 10 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Establishment Of Sister Chromatid Cohesion
Sister chromatid cohesion refers to the process by which sister chromatids are paired and held together during certain phases of the cell cycle. Establishment of sister chromatid cohesion is the process by which chromatin-associated cohesin protein becomes competent to physically bind together the sister chromatids. In general, cohesion is established during S phase as DNA is replicated, and is lost when chromosomes segregate during mitosis and meiosis. Some studies have suggested that cohesion aids in aligning the kinetochores during mitosis by forcing the kinetochores to face opposite cell poles. Cohesin loading Cohesin first associates with the chromosomes during G1 phase. The cohesin ring is composed of two SMC protein, SMC (structural maintenance of chromosomes) proteins and two additional Scc proteins. Cohesin may originally interact with chromosomes via the ATPase domains of the SMC proteins. In yeast, the loading of cohesin on the chromosomes depends on proteins Scc2 and Scc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
STAG2
Cohesin subunit SA-2 (SA2) is a protein that in humans is encoded by the ''STAG2'' gene. SA2 is a subunit of the Cohesin complex which mediates sister chromatid cohesion, homologous recombination and DNA looping. In somatic cells cohesin is formed of SMC3, SMC1, RAD21 and either SA1 or SA2 whereas in meiosis, cohesin is formed of SMC3, SMC1B, REC8 and SA3. ''STAG2'' is frequently mutated in a range of cancers and several other disorders. Function SA2 is part of the cohesin complex, which is a structure that holds the sister chromatids together after DNA replication. STAG2 has been shown to interact with STAG1. Cohesion folds by DNA loop extrusion and this cohesion consists of SMC1, SMC3, RAD21, and either STAG1 or STAG2. SA2 interacts with a ring-like structure composed of SMC1A, SMC3, and RAD21, to form the core of the cohesin complex. The ring-like structure binds chromosomes together until degradation of the cohesin complex is finished during cell division. This ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kim Nasmyth
Kim Ashley Nasmyth (born 18 October 1952) is an English geneticist, the Whitley Professor of Biochemistry at the University of Oxford, a Fellow of Trinity College, Oxford, former scientific director of the Research Institute of Molecular Pathology (IMP), and former head of the Department of Biochemistry, University of Oxford. He is best known for his work on the segregation of chromosomes during cell division. Early life and education Nasmyth was born in London in 1952 of James Ashley (Jan) Nasmyth and Jenny Hughes. His father Jan was doubly descended from Charles II of England, King Charles II and founder of the billion dollar publishing company Argus Media. He attended Eton College, Berkshire, then the University of York, where he studied Biology. Nasmyth went on to complete his graduate studies in the group of Murdoch Mitchison at the University of Edinburgh. Here he worked on the cell cycle alongside Paul Nurse and his PhD thesis focused on the control of DNA replication in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
WAPAL
Wings apart-like protein homolog (WAPL) is a protein that in humans is encoded by the ''WAPAL'' gene. WAPL is a key regulator of the Cohesin complex which mediates Establishment of sister chromatid cohesion, sister chromatid cohesion, homologous recombination and Topologically associating domain, DNA looping. Cohesin is formed of SMC3, SMC1A, SMC1, RAD21 and either STAG1, SA1 or STAG2, SA2. Cohesin has a ring-like arrangement and it is thought that it associates with the chromosome by entrapping it whether as a loop of DNA, a single strand or a pair of sister chromosomes. WAPL forms a complex with PDS5A or PDS5B and releases cohesin from DNA by opening the interface between SMC3 and RAD21. Interphase Cohesin loading begins in telophase and is mediated by NIPBL and its binding partner MAU2. In Cell cycle, G1, WAPL forms a complex with PDS5 and removes cohesin from the DNA but it is reloaded by NIPBL-MAU2. The equilibrium between loading and release give cohesin a DNA residence ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SMC1A
Structural maintenance of chromosomes protein 1A (SMC1A) is a protein that in humans is encoded by the ''SMC1A'' gene. SMC1A is a subunit of the cohesin complex which mediates sister chromatid cohesion, homologous recombination and DNA looping. In somatic cells, cohesin is formed of SMC1A, SMC3, RAD21 and either SA1 or SA2 whereas in meiosis, cohesin is formed of SMC3, SMC1B, REC8 and SA3. SMC1A is a member of the SMC protein family. Members of this family are key regulators of DNA repair, chromosome condensation and chromosome segregation from bacteria to humans. Structure The domain organisation of SMC proteins is highly conserved and is composed of an N-terminal Walker A motif, coiled-coil, "hinge", coiled-coil and a C-terminal Walker B motif. The protein folds back on itself to form a rod-shaped molecule with a heterodimerisation "hinge" domain at one end and an ABC-type ATPase "head" at the other. These globular domains are separated by a ~50 nm anti-parall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NIPBL
Nipped-B-like protein (NIPBL), also known as SCC2 or delangin is a protein that in humans is encoded by the ''NIPBL'' gene. NIPBL is required for the association of cohesin with DNA and is the major subunit of the cohesin loading complex. Heterozygous mutations in ''NIPBL'' account for an estimated 60% of case of Cornelia de Lange Syndrome. Structure and Interactions NIPBL is a large hook-shaped protein containing HEAT repeats. NIPBL forms a complex with MAU2 (Scc4 in budding yeast) known as the cohesin loading complex. As this name suggests NIPBL and MAU2 are required for the initial association of cohesin with DNA. Cohesin is thought to mediate enhancer-promoter interactions and generate Topologically associating domains (TADs). As well as mediating cohesion and regulating DNA architecture the cohesin complex is required for DNA repair by homologous recombination. Given that NIPBL is required for cohesin's association with DNA it is thought that NIPBL is also required for a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SMC Protein
SMC proteins represent a large family of ATPases that participate in many aspects of higher-order chromosome organization and dynamics. SMC proteins are widely conserved across bacteria, archaea, and eukaryotes. In eukaryotes, they function as the core ATPase subunits of large protein complexes such as condensin, cohesin, and SMC5/6. The term SMC derives from a mutant strain of ''Saccharomyces cerevisiae'' named ''smc1'' (stability of mini-chromosomes 1), which was identified based on its defect in maintaining the stability of mini-chromosomes. After the gene product of ''SMC1'' was characterized, and homologous proteins were found to be essential for chromosome structure and dynamics in many organisms, the acronym SMC was redefined to stand for "Structural Maintenance of Chromosomes". Classification Eukaryotic SMCs Eukaryotes have at least six SMC proteins in individual organisms, and they form three distinct heterodimers with specialized functions: *SMC1-SMC3: A pair of SM ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SMC Proteins
SMC proteins represent a large family of ATPases that participate in many aspects of higher-order chromosome organization and dynamics. SMC proteins are widely conserved across bacteria, archaea, and eukaryotes. In eukaryotes, they function as the core ATPase subunits of large protein complexes such as condensin, cohesin, and SMC5/6. The term SMC derives from a mutant strain of ''Saccharomyces cerevisiae'' named ''smc1'' (stability of mini-chromosomes 1), which was identified based on its defect in maintaining the stability of mini-chromosomes. After the gene product of ''SMC1'' was characterized, and homologous proteins were found to be essential for chromosome structure and dynamics in many organisms, the acronym SMC was redefined to stand for "Structural Maintenance of Chromosomes". Classification Eukaryotic SMCs Eukaryotes have at least six SMC proteins in individual organisms, and they form three distinct heterodimers with specialized functions: *SMC1-SMC3: A pair of SMC ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
