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Lamin B Receptor
Lamin-B receptor is a protein, and in humans, it is encoded by the ''LBR'' gene. Function The protein encoded by this gene belongs to the ERG4/ ERG24 family. It localizes to the inner membrane of the nuclear envelope and anchors the lamina and the heterochromatin to the membrane. It may mediate the interaction between chromatin and lamin B. Mutations of this gene has been associated with autosomal recessive HEM/Greenberg skeletal dysplasia. Alternative splicing occurs at this locus and two transcript variants encoding the same protein have been identified. Clinical significance There is evidence tying it to Greenberg dysplasia and Pelger-Huet anomaly. Interactions Lamin B receptor has been shown to interact with CBX3 and CBX5. LBR also interacts with long non-coding RNA XIST in mouse cells and potentially assist the spreading XIST across X chromosome The X chromosome is one of the two sex-determining chromosomes (allosomes) in many organisms, including mammals (th ... [...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 residue ... [...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 gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ERG4
ERG4 or Delta(24(24(1)))-sterol reductase or Delta(24(28))-sterol reductase is an enzyme that catalyzes the last step of ergosterol biosynthesis pathway in fungi ''Saccharomyces cerevisiae ''Saccharomyces cerevisiae'' () (brewer's yeast or baker's yeast) is a species of yeast (single-celled fungus microorganisms). The species has been instrumental in winemaking, baking, and brewing since ancient times. It is believed to have been o ...'' (Baker's yeast), which 5,7,22,24(28)- ergostatetraenol converted into ergosterol. References EC 1.3.1 Saccharomyces cerevisiae genes {{Enzyme-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ERG24
In enzymology, a Delta14-sterol reductase () is an enzyme that catalyzes the chemical reaction :4,4-dimethyl-5alpha-cholesta-8,24-dien-3beta-ol + NADP+ \rightleftharpoons 4,4-dimethyl-5alpha-cholesta-8,14,24-trien-3beta-ol + NADPH + H+ Thus, the two substrates of this enzyme are 4,4-dimethyl-5alpha-cholesta-8,24-dien-3beta-ol and NADP+, whereas its 3 products are 4,4-dimethyl-5alpha-cholesta-8,14,24-trien-3beta-ol, NADPH, and H+. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-CH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is 4,4-dimethyl-5alpha-cholesta-8,24-dien-3beta-ol:NADP+ Delta14-oxidoreductase. This enzyme participates in biosynthesis of steroids A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inner Nuclear Membrane Proteins
Inner nuclear membrane proteins (INM proteins) are membrane proteins that are embedded in or associated with the inner membrane of the nuclear envelope. There are about 60 INM proteins, most of which are poorly characterized with respect to structure and function. Among the few well-characterized INM proteins are lamin B receptor (LBR), lamina-associated polypeptide 1 (LAP1), lamina-associated polypeptide-2 (LAP2), emerin and MAN1. Common structural features Several integral nuclear membrane proteins of different size and structure have been identified. It is proposed that they share some structural features with respect to nucleoplasmic domain(s) and lipid-soluble domain(s). Some INM proteins contain common protein domain structures, and can thus be categorised into known protein domain families. These include the LEM-, SUN-, and KASH-domain families. Members of the LEM-domain family play a part in chromatin organisation . SUN- and KASH-domains participate in linking t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Envelope
The nuclear envelope, also known as the nuclear membrane, is made up of two lipid bilayer membranes that in eukaryotic cells surround the nucleus, which encloses the genetic material. The nuclear envelope consists of two lipid bilayer membranes: an inner nuclear membrane and an outer nuclear membrane. The space between the membranes is called the perinuclear space. It is usually about 10–50 nm wide. The outer nuclear membrane is continuous with the endoplasmic reticulum membrane. The nuclear envelope has many nuclear pores that allow materials to move between the cytosol and the nucleus. Intermediate filament proteins called lamins form a structure called the nuclear lamina on the inner aspect of the inner nuclear membrane and give structural support to the nucleus. Structure The nuclear envelope is made up of two lipid bilayer membranes, an inner nuclear membrane and an outer nuclear membrane. These membranes are connected to each other by nuclear pores. Two sets of in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterochromatin
Heterochromatin is a tightly packed form of DNA or '' condensed DNA'', which comes in multiple varieties. These varieties lie on a continue between the two extremes of constitutive heterochromatin and facultative heterochromatin. Both play a role in the expression of genes. Because it is tightly packed, it was thought to be inaccessible to polymerases and therefore not transcribed; however, according to Volpe et al. (2002), and many other papers since, much of this DNA is in fact transcribed, but it is continuously turned over via RNA-induced transcriptional silencing (RITS). Recent studies with electron microscopy and OsO4 staining reveal that the dense packing is not due to the chromatin. Constitutive heterochromatin can affect the genes near itself (e.g. position-effect variegation). It is usually repetitive and forms structural functions such as centromeres or telomeres, in addition to acting as an attractor for other gene-expression or repression signals. Facultative hete ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lamin B
Lamin B2 is a protein that in humans is encoded by the ''LMNB2'' gene. It is the second of two type B nuclear lamins, and it is associated with laminopathies. Model organisms Model organisms have been used in the study of Lamin B2 function. A conditional knockout mouse line, called ''Lmnb2tm1a(KOMP)Wtsi'' was generated as part of the International Knockout Mouse Consortium program — a high-throughput mutagenesis project to generate and distribute animal models of disease to interested scientists. Male and female animals underwent a standardized phenotypic screen to determine the effects of deletion. Twenty four tests were carried out on mutant mice and four significant abnormalities were observed. No homozygous mutant embryos were identified during gestation, and therefore none survived until weaning. The remaining tests were carried out on heterozygous mutant adult mice. Male heterozygotes displayed increased circulating creatinine levels and an increased susceptibility to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greenberg Dysplasia
Hydrops-ectopic calcification-moth-eaten skeletal dysplasia is a defect in cholesterol biosynthesis. Greenberg characterized the condition in 1988. It has been associated with the lamin B receptor. Signs and Symptoms Hydrops-ectopic calcification-moth-eaten skeletal dysplasia causes the bones in a fetus to develop abnormally. This leads to a characteristic "moth eaten" appearance of the bones when viewed under an X-ray. Micromelia, polydactyly and ectopic calcification, or the built up of calcium in the soft tissues of the body, may all occur. Eighty to ninety nine percent of effected individuals will have abnormally ossified vertebrae, abnormal pelvis bone ossification, anterior rib punctate calcifications and brachydactyly. The second defining feature of hydrops-ectopic calcification-moth-eaten skeletal dysplasia is hydrops fetalis Hydrops foetalis or hydrops fetalis is a condition in the fetus characterized by an accumulation of fluid, or edema, in at least two fetal c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CBX3
Chromobox protein homolog 3 is a protein that is encoded by the ''CBX3'' gene in humans. At the nuclear envelope, the nuclear lamina and heterochromatin are adjacent to the inner nuclear membrane. The protein encoded by this gene binds DNA and is a component of heterochromatin. This protein also can bind lamin B receptor, an integral membrane protein found in the inner nuclear membrane. The dual binding functions of the encoded protein may explain the association of heterochromatin with the inner nuclear membrane. Two transcript variants encoding the same protein but differing in the 5' UTR, have been found for this gene. Interactions CBX3 has been shown to interact with PIM1, Ki-67, Lamin B receptor, CBX5 and CBX1. See also * Heterochromatin protein 1 The family of heterochromatin protein 1 (HP1) ("Chromobox Homolog", CBX) consists of highly conserved proteins, which have important functions in the cell nucleus. These functions include gene repression by heterochromatin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
