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Clathrin

 

 
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Clathrin
 
 
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Clathrin is a protein
Protein

Proteins are organic compounds made of amino acids arranged in a linear chain and joined together by peptide bonds between the carboxyl and amino groups of adjacent amino acid Residue ....
 that is the major constituent of the 'coat' of the clathrin-coated pits and coated vesicle
Vesicle

Vesicle may refer to:* Synaptic vesicle* Auditory vesicle* Optic vesicles* Seminal vesicle* Subsporangial vesicle* Vesical arteries* Vesicle , a relatively small and enclosed compartment within a cell...
s formed during endocytosis
Endocytosis

Endocytosis is the process by which cell s absorb material from outside the cell by engulfing it with their cell membrane. It is used by all cells of the body because most substances important to them are large Chemical polarity molecules that cannot pass through the hydrophobic plasma membrane or cell membrane....
 of materials at the surface of cells.

Clathrin molecules are recruited with the aid of adaptor proteins to a membrane segment that is destined to be incorporated into a vesicle. In synaptic vesicle formation, one such adaptor protein is AP180
Ap180

AP180 is a protein that plays an important role in clathrin-mediated endocytosis of synaptic vesicles. It is capable of simultaneously binding both membrane lipids and clathrin and is therefore thought to recruit clathrin to the membrane of newly invagination vesicles....
 ().






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Encyclopedia


Clathrin is a protein
Protein

Proteins are organic compounds made of amino acids arranged in a linear chain and joined together by peptide bonds between the carboxyl and amino groups of adjacent amino acid Residue ....
 that is the major constituent of the 'coat' of the clathrin-coated pits and coated vesicle
Vesicle

Vesicle may refer to:* Synaptic vesicle* Auditory vesicle* Optic vesicles* Seminal vesicle* Subsporangial vesicle* Vesical arteries* Vesicle , a relatively small and enclosed compartment within a cell...
s formed during endocytosis
Endocytosis

Endocytosis is the process by which cell s absorb material from outside the cell by engulfing it with their cell membrane. It is used by all cells of the body because most substances important to them are large Chemical polarity molecules that cannot pass through the hydrophobic plasma membrane or cell membrane....
 of materials at the surface of cells.

Clathrin molecules are recruited with the aid of adaptor proteins to a membrane segment that is destined to be incorporated into a vesicle. In synaptic vesicle formation, one such adaptor protein is AP180
Ap180

AP180 is a protein that plays an important role in clathrin-mediated endocytosis of synaptic vesicles. It is capable of simultaneously binding both membrane lipids and clathrin and is therefore thought to recruit clathrin to the membrane of newly invagination vesicles....
 (). This protein both recruits clathrin to membranes and also promotes its polymerisation in a localized polyhedral
Polyhedron

|}A polyhedron is often defined as a geometry object with flat faces and straight edges .This definition of a polyhedron is not very precise, and to a modern mathematician is quite unsatisfactory....
 lattice on the plasma membrane. Epsin
Epsin

Epsins are the family of plasma membrane proteins that are important in creating the needed membrane curvature. Epsins contribute to various needed membrane deformations like endocytosis and block vesicle formation during mitosis....
 can also recruit clathrin to membranes and promote its polymerisation, and, in this case, the epsin helps deform the membrane and thus clathrin coated vesicles can bud (). After vesicle scission, the coat quickly falls off and may then be reused to form fresh-coated pits and vesicles. The un-coated vesicle then fuses with endosomes, delivering its contents to them; this membrane is ultimately returned
Endocytic cycle

Most animal cells take up portions of their surface plasma membranes in a process called endocytosis. The main route of endocytosis is the coated pit which buds into a cell to form a cytoplasmic vesicle ? a clathrin-coated vesicle....
 to the cell surface.

Summary:
  • 1) In response to a stimulus (eg. receptor tyrosine kinase meets a ligand), adaptin binds to the C-terminus of many molecules on the cell surface
  • 2) The clathrin heavy and light chains will bind to and polymerize around the vesicle, which will pinch off
  • 3) Unlike COPI
    COPI

    COPI is a protein that coats vesicle s that transports proteins from the cis end of the Golgi complex to the rough endoplasmic reticulum . This type of transport is termed retrograde transport....
     and COPII
    COPII

    COPII is a type of vesicle that transports proteins from the rough endoplasmic reticulum to the Golgi apparatus. This is termed anterograde transport....
    , a piece of the membrane is pinched off, mediated by dynamin
  • 4) Once clathrin coated vesicles have separated, clathrin coats disassemble to leave the naked transport vesicle
  • 5) Vesicles are transported by mechanisms associated with microtubules within the cell, and then fuse with other membrane structures (eg. endosomes).


A similar process also buds membrane segments from intracellular organelle
Organelle

In cell biology, an organelle is a specialized subunit within a cell that has a specific function, and is usually separately enclosed within its own lipid membrane....
s, such as in the formation of vesicles from the trans-Golgi network
Golgi

Golgi may refer to the physician Camillo Golgi or one of the structures named after him:*Golgi apparatus in some cells*Golgi tendon organ...
.

Clathrin was first isolated and named by Barbara Pearse
Barbara Pearse

Barbara Pearse is a British biological scientist and Fellow of the Royal Society. She works at the Medical Research Council Laboratory of Molecular Biology in Cambridge, United Kingdom....
 in 1975.

See also

  • AP180
    Ap180

    AP180 is a protein that plays an important role in clathrin-mediated endocytosis of synaptic vesicles. It is capable of simultaneously binding both membrane lipids and clathrin and is therefore thought to recruit clathrin to the membrane of newly invagination vesicles....
  • Cap formation
    Cap formation

    When molecules on the surface of a cell are crosslinked, they are moved to one end of the cell to form a ?cap?. This phenomenon, the process of which is called cap formation, was discovered in 1971 on lymphocytes and is a property of amoebae and all locomotory animal cells except sperm....
  • Cell migration
    Cell migration

    Cell migration is a central process in the development and maintenance of multicellular organisms. Tissue formation during embryogenesis, wound healing and immune systems all require the orchestrated movement of cells in a particular direction to a specific location....
  • Endocytic cycle
    Endocytic cycle

    Most animal cells take up portions of their surface plasma membranes in a process called endocytosis. The main route of endocytosis is the coated pit which buds into a cell to form a cytoplasmic vesicle ? a clathrin-coated vesicle....
  • Epsin
    Epsin

    Epsins are the family of plasma membrane proteins that are important in creating the needed membrane curvature. Epsins contribute to various needed membrane deformations like endocytosis and block vesicle formation during mitosis....
  • Synaptic vesicle
    Synaptic vesicle

    In a neuron synaptic vesicles or neurotransmitter vesicles store various neurotransmitters that are exocytosis at the chemical synapse. The release is regulated by a calcium channel....
  • Adaptin
    Adaptin

    Adaptin is a protein mediating the formation of clathrin-coated pits, through interaction with membrane-bound Receptor s. There are several types of adaptin, each related to a different group of such receptors....


External links

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