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Coatomer
The coatomer is a protein complex that coats membrane-bound transport vesicles. Two types of coatomers are known: *COPI (retrograde transport from trans-Golgi network to cis-Golgi network and endoplasmic reticulum) *COPII (anterograde transport from ER to the cis-Golgi) Coatomers are functionally analogous and evolutionarily homologous to clathrin adaptor proteins, also known as adaptins, which regulate endocytosis from the plasma membrane and transport from the trans-Golgi network to lysosomes. Structure The coatomer protein complex is made up of seven nonidentical protein subunits. These seven nonidentical protein subunits are part of two protein subcomplexes. The first subcomplex consists of Ret1(α-COP), Sec27(β’-COP), and Sec 28(ε-COP). The second subcomplex consists of Sec26 (β-COP), Sec21 (γ-COP), Ret2(δ-COP), and Ret3 (ζ-COP). COP I COPI is a coatomer that coats the vesicles transporting proteins from the Golgi complex to the ER. This pathway is referred to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
COPI
COPI is a coatomer, a protein complex that coats vesicles transporting proteins from the ''cis'' end of the Golgi complex The Golgi apparatus (), also known as the Golgi complex, Golgi body, or simply the Golgi, is an organelle found in most eukaryotic cells. Part of the endomembrane system in the cytoplasm, it packages proteins into membrane-bound vesicles insi ... back to the rough endoplasmic reticulum (ER), where they were originally Translation (genetics), synthesized, and between Golgi compartments. This type of transport is ''retrograde transport'', in contrast to the ''anterograde transport'' associated with the COPII protein. The name "COPI" refers to the specific coat protein complex that initiates the budding process on the ''cis''-Golgi membrane. The coat consists of large protein subcomplexes that are made of seven different protein subunits, namely α, β, β', γ, Archain, δ, ε and COPZ1, ζ. Coat proteins Coat protein, or COPI, is an ADP ribosylation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ARF1
ADP-ribosylation factor 1 is a protein that in humans is encoded by the ''ARF1'' gene. Function ADP-ribosylation factor 1 (ARF1) is a member of the human ARF gene family. The family members encode small guanine nucleotide-binding proteins that stimulate the ADP-ribosyltransferase activity of cholera toxin and play a role in vesicular trafficking as activators of phospholipase D. The gene products, including 6 ARF proteins and 11 ARF-like proteins, constitute a family of the RAS superfamily. The ARF proteins are categorized as class I (ARF1, ARF2 and ARF3), class II (ARF4 and ARF5) and class III (ARF6), and members of each class share a common gene organization. The ARF1 protein is localized to the Golgi apparatus and has a central role in intra-Golgi transport. Multiple alternatively spliced transcript variants encoding the same protein have been found for this gene. The major mechanism of action of Brefeldin A is through inhibition of ARF1. Interactions ARF1 has been shown ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clathrin Adaptor Protein
Clathrin adaptor proteins, also known as adaptins, are vesicular transport adaptor proteins associated with clathrin. These proteins are synthesized in the ribosomes, processed in the endoplasmic reticulum and transported from the Golgi apparatus to the trans-Golgi network, and from there via small carrier vesicles to their final destination compartment. The association between adaptins and clathrin are important for vesicular cargo selection and transporting. Clathrin coats contain both clathrin (acts as a scaffold) and adaptor complexes that link clathrin to receptors in coated vesicles. Clathrin-associated protein complexes are believed to interact with the cytoplasmic tails of membrane proteins, leading to their selection and concentration. Therefore, adaptor proteins are responsible for the recruitment of cargo molecules into a growing clathrin-coated pits. The two major types of clathrin adaptor complexes are the heterotetrameric vesicular transport adaptor proteins (AP1-5), a ... [...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] |
SAR1A
The Coat Protein Complex II, or COPII, is a group of proteins that facilitate the formation of vesicles to transport proteins from the endoplasmic reticulum to the Golgi apparatus or endoplasmic-reticulum–Golgi intermediate compartment. This process is termed anterograde transport, in contrast to the retrograde transport associated with the COPI complex. COPII is assembled in two parts: first an inner layer of Sar1, Sec23, and Sec24 forms; then the inner coat is surrounded by an outer lattice of Sec13 and Sec31. Function The COPII coat is responsible for the formation of vesicles from the endoplasmic reticulum (ER). These vesicles transport cargo proteins to the Golgi apparatus (in yeast) or the endoplasmic-reticulum-Golgi intermediate compartment (ERGIC, in mammals). Coat assembly is initiated when the cytosolic Ras GTPase Sar1 is activated by its guanine nucleotide exchange factor Sec12. Activated Sar1-GTP inserts itself into the ER membrane, binding preferentially to are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
KDEL (amino Acid Sequence)
KDEL is a target peptide sequence in mammals and plants located on the C-terminal end of the amino acid structure of a protein. The KDEL sequence prevents a protein from being secreted from the endoplasmic reticulum (ER) and facilitates its return if it is accidentally exported. A protein with a functional KDEL motif will be retrieved from the Golgi apparatus by retrograde transport to the ER lumen. It also targets proteins from other locations (such as the cytoplasm) to the ER. Proteins can only leave the ER after this sequence has been cleaved off. The abbreviation KDEL is formed by the corresponding letters to each amino acid. This letter system was defined by the IUPAC and IUBMB in 1983, and is as follows: *K—Lysine *D—Aspartic acid *E—Glutamic acid *L—Leucine Therefore, the KDEL sequence in three letter code is: Lysine, Lys-Aspartic acid, Asp-Glutamic acid, Glu-Leucine, Leu. The soluble resident protein will remain in the ER as long as it contains a KDEL signal seq ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transmembrane Protein
A transmembrane protein (TP) is a type of integral membrane protein that spans the entirety of the cell membrane. Many transmembrane proteins function as gateways to permit the transport of specific substances across the membrane. They frequently undergo significant conformational changes to move a substance through the membrane. They are usually highly hydrophobic and aggregate and precipitate in water. They require detergents or nonpolar solvents for extraction, although some of them (beta-barrels) can be also extracted using denaturing agents. The peptide sequence that spans the membrane, or the transmembrane segment, is largely hydrophobic and can be visualized using the hydropathy plot. Depending on the number of transmembrane segments, transmembrane proteins can be classified as single-span (or bitopic) or multi-span (polytopic). Some other integral membrane proteins are called monotopic, meaning that they are also permanently attached to the membrane, but do not pass ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lumen (anatomy)
In biology, a lumen (plural lumina) is the inside space of a tubular structure, such as an artery or intestine. It comes . It can refer to: *The interior of a vessel, such as the central space in an artery, vein or capillary through which blood flows. *The interior of the gastrointestinal tract *The pathways of the bronchi in the lungs *The interior of renal tubules and urinary collecting ducts *The pathways of the female genital tract, starting with a single pathway of the vagina, splitting up in two lumina in the uterus, both of which continue through the Fallopian tubes In cell biology, a lumen is a membrane-defined space that is found inside several organelles, cellular components, or structures: *thylakoid, endoplasmic reticulum, Golgi apparatus, lysosome, mitochondrion, or microtubule Transluminal procedures ''Transluminal procedures'' are procedures occurring through lumina, including: *Natural orifice transluminal endoscopic surgery in the lumina of, for example, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
P24 Protein Family
P24 protein family is a group of transmembrane proteins that are major components of COPI and COPII-coated vesicles. The family is also known as EMP24/GP25L/p24 family and TMP21-like proteins. The latter naming was after transmembrane emp24 domain-containing protein 10 that was found in the human brain. It was claimed to block the beta-amyloid peptide, which is implicated in the pathogenesis of Alzheimer's disease. Function p24 family proteins localize to the major organelles of the early secretory pathway: the endoplasmic reticulum and the Golgi apparatus, where they seem to be involved in trafficking between the two compartments. In yeast, all p24 family proteins can be removed, causing only a mild phenotype. However, in mammals at least some p24 proteins are essential for survival, e.g. removal of p24δ1 is lethal in mice. p24 family members have been implicated in the biogenesis of COPI and COPII-coated vesicles, transporting membrane-bound proteins through the secretory s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Dimer
In biochemistry, a protein dimer is a macromolecular complex formed by two protein monomers, or single proteins, which are usually non-covalently bound. Many macromolecules, such as proteins or nucleic acids, form dimers. The word ''dimer'' has roots meaning "two parts", '' di-'' + '' -mer''. A protein dimer is a type of protein quaternary structure. A protein homodimer is formed by two identical proteins. A protein heterodimer is formed by two different proteins. Most protein dimers in biochemistry are not connected by covalent bonds. An example of a non-covalent heterodimer is the enzyme reverse transcriptase, which is composed of two different amino acid chains. An exception is dimers that are linked by disulfide bridges such as the homodimeric protein NEMO. Some proteins contain specialized domains to ensure dimerization (dimerization domains) and specificity. The G protein-coupled cannabinoid receptors have the ability to form both homo- and heterodimers with several ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amphiphile
An amphiphile (from the Greek αμφις amphis, both, and φιλíα philia, love, friendship), or amphipath, is a chemical compound possessing both hydrophilic (''water-loving'', polar) and lipophilic (''fat-loving'') properties. Such a compound is called amphiphilic or amphipathic. Common amphiphilic substances are soaps, detergents, and lipoproteins. The phospholipid amphiphiles are the major structural component of cell membranes. Amphiphiles are the basis for a number of areas of research in chemistry and biochemistry, notably that of lipid polymorphism. Organic compounds containing hydrophilic groups at both ends of the molecule are called bolaamphiphilic. The micelles they form in the aggregate are prolate. Structure The lipophilic group is typically a large hydrocarbon moiety, such as a long chain of the form CH3(CH2)n, with n > 4. The hydrophilic group falls into one of the following categories: # charged groups #* anionic. Examples, with the lipophilic part of the m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lipid Bilayer
The lipid bilayer (or phospholipid bilayer) is a thin polar membrane made of two layers of lipid molecules. These membranes are flat sheets that form a continuous barrier around all cells. The cell membranes of almost all organisms and many viruses are made of a lipid bilayer, as are the nuclear membrane surrounding the cell nucleus, and membranes of the membrane-bound organelles in the cell. The lipid bilayer is the barrier that keeps ions, proteins and other molecules where they are needed and prevents them from diffusing into areas where they should not be. Lipid bilayers are ideally suited to this role, even though they are only a few nanometers in width, because they are impermeable to most water-soluble (hydrophilic) molecules. Bilayers are particularly impermeable to ions, which allows cells to regulate salt concentrations and pH by transporting ions across their membranes using proteins called ion pumps. Biological bilayers are usually composed of amphiphilic phosphol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
