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AP4S1
AP-4 complex subunit sigma-1 is a protein that in humans is encoded by the ''AP4S1'' gene. Function The heterotetrameric adaptor protein (AP) complexes sort integral membrane proteins at various stages of the endocytic and secretory pathways. AP4 is composed of 2 large chains, beta-4 ( AP4B1) and epsilon-4 ( AP4E1), a medium chain, mu-4 (AP4M1), and a small chain, sigma-4 (AP4S1, this gene). Clinical relevance Deficiency of AP-4 leads to childhood-onset hereditary spastic paraplegia and it is currently hypothesized that AP4-complex-mediated trafficking plays a crucial role in brain development and functioning. See also * AP2 adaptor complex The AP2 adaptor complex is a multimeric protein that works on the cell membrane to internalize cargo in clathrin-mediated endocytosis. It is a stable complex of four adaptins which give rise to a structure that has a core domain and two appendage d ... References External links * Further reading * * {{refend Proteins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AP4E1
AP-4 complex subunit epsilon-1 is a protein that in humans is encoded by the ''AP4E1'' gene. Function The heterotetrameric adaptor protein (AP) complexes sort integral membrane proteins at various stages of the endocytic and secretory pathways. AP4 is composed of 2 large chains, beta-4 ( AP4B1) and epsilon-4 (AP4E1; this gene), a medium chain, mu-4 (AP4M1), and a small chain, sigma-4 (AP4S1). Clinical relevance It is currently hypothesized that AP4-complex-mediated trafficking plays a crucial role in brain development and functioning. Model organisms Model organisms have been used in the study of AP4E1 function. A conditional knockout mouse line, called ''Ap4e1tm1a(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 dele ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AP4B1
AP-4 complex subunit beta-1 is a protein that in humans is encoded by the ''AP4B1'' gene. Function The heterotetrameric adaptor protein (AP) complexes sort integral membrane proteins at various stages of the endocytic and secretory pathways. AP4 is composed of 2 large chains, beta-4 (AP4B1, this protein) and epsilon-4 (AP4E1), a medium chain, mu-4 (AP4M1), and a small chain, sigma-4 (AP4S1) Interactions AP4B1 has been shown to interact with AP4M1 AP-4 complex subunit mu-1 is a protein that in humans is encoded by the ''AP4M1'' gene. Function This gene encodes a subunit of the heterotetrameric AP-4 complex. The encoded protein belongs to the adaptor complexes medium subunits family. Thi .... Clinical relevance AP4-complex-mediated trafficking plays a crucial role in brain development and functioning. References External links * PDBe-KBprovides an overview of all the structure information available in the PDB for Human AP-4 complex subunit beta-1 Further readin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hereditary Spastic Paraplegia
Hereditary spastic paraplegia (HSP) is a group of inherited diseases whose main feature is a progressive gait disorder. The disease presents with progressive stiffness (spasticity) and contraction in the lower limbs. HSP is also known as hereditary spastic paraparesis, familial spastic paraplegia, French settlement disease, Strumpell disease, or Strumpell-Lorrain disease. The symptoms are a result of dysfunction of long axons in the spinal cord. The affected cells are the primary motor neurons; therefore, the disease is an upper motor neuron disease. HSP is not a form of cerebral palsy even though it physically may appear and behave much the same as spastic diplegia. The origin of HSP is different from cerebral palsy. Despite this, some of the same anti-spasticity medications used in spastic cerebral palsy are sometimes used to treat HSP symptoms. HSP is caused by defects in transport of proteins, structural proteins, cell-maintaining proteins, lipids, and other substances 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] |
Heterotetrameric
A tetrameric protein is a protein with a quaternary structure of four subunits (tetrameric). Homotetramers have four identical subunits (such as glutathione S-transferase), and heterotetramers are complexes of different subunits. A tetramer can be assembled as dimer of dimers with two homodimer subunits (such as sorbitol dehydrogenase), or two heterodimer subunits (such as hemoglobin). Subunit interactions in tetramers The interactions between subunits forming a tetramer is primarily determined by non covalent interaction. Hydrophobic effects, hydrogen bonds and electrostatic interactions are the primary sources for this binding process between subunits. For homotetrameric proteins such as Sorbitol dehydrogenase (SDH), the structure is believed to have evolved going from a monomeric to a dimeric and finally a tetrameric structure in evolution. The binding process in SDH and many other tetrameric enzymes can be described by the gain in free energy which can be determined fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adaptor Proteins, Vesicular Transport
Vesicular transport adaptor proteins are proteins involved in forming complexes that function in the trafficking of molecules from one subcellular location to another. These complexes concentrate the correct cargo molecules in vesicles that bud or extrude off of one organelle and travel to another location, where the cargo is delivered. While some of the details of how these adaptor proteins achieve their trafficking specificity has been worked out, there is still much to be learned. There are several human disorders associated with defects in components of these complexes including Alzheimer's and Parkinson's diseases. The proteins Most of the adaptor proteins are heterotetramers. In the AP complexes, there are two large proteins ( ∼100 k D) and two smaller proteins. One of the large proteins is termed β (beta), with β1 in the AP-1 complex, β2 in the AP-2 complex, and so on. The other large protein has different designations in the different complexes. In AP-1 i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Sorting
:''This article deals with protein targeting in eukaryotes unless specified otherwise.'' Protein targeting or protein sorting is the biological mechanism by which proteins are transported to their appropriate destinations within or outside the cell. Proteins can be targeted to the inner space of an organelle, different intracellular membranes, the plasma membrane, or to the exterior of the cell via secretion. Information contained in the protein itself directs this delivery process. Correct sorting is crucial for the cell; errors or dysfunction in sorting have been linked to multiple diseases. History In 1970, Günter Blobel conducted experiments on protein translocation across membranes. Blobel, then an assistant professor at Rockefeller University, built upon the work of his colleague George Palade. Palade had previously demonstrated that non-secreted proteins were translated by free ribosomes in the cytosol, while secreted proteins (and target proteins, in general) were tran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AP4M1
AP-4 complex subunit mu-1 is a protein that in humans is encoded by the ''AP4M1'' gene. Function This gene encodes a subunit of the heterotetrameric AP-4 complex. The encoded protein belongs to the adaptor complexes medium subunits family. This AP-4 complex is involved in the recognition and sorting of cargo proteins with tyrosine-based motifs from the trans-golgi network to the endosomal-lysosomal system. Interactions AP4M1 has been shown to interact with AP4B1 AP-4 complex subunit beta-1 is a protein that in humans is encoded by the ''AP4B1'' gene. Function The heterotetrameric adaptor protein (AP) complexes sort integral membrane proteins at various stages of the endocytic and secretory pathways. A .... Clinical relevance The AP4-complex-mediated trafficking plays a crucial role in brain development and functioning. References External links * * Further reading * * * * * * * * {{gene-7-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AP2 Adaptor Complex
The AP2 adaptor complex is a multimeric protein that works on the cell membrane to internalize cargo in clathrin-mediated endocytosis. It is a stable complex of four adaptins which give rise to a structure that has a core domain and two appendage domains attached to the core domain by polypeptide linkers. These appendage domains are sometimes called 'ears'. The core domain binds to the membrane and to cargo destined for internalisation. The alpha and beta appendage domains bind to accessory proteins and to clathrin. Their interactions allow the temporal and spatial regulation of the assembly of clathrin-coated vesicles and their endocytosis. The AP-2 complex is a heterotetramer consisting of two large adaptins (α and β), a medium adaptin (μ), and a small adaptin (σ): * complex 2 ** AP2A1 (α unit 1) ** AP2A2 (α unit 2) ** AP2B1 (β unit) ** AP2M1 (μ unit) ** AP2S1 (σ unit) Structure The AP2 adaptor complex exists in two primary conformations: the open conformation (active ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
