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Encyclopedia > Laminin

Laminins are the major non-collagenous component of the basal lamina, such as those on which cells of an epithelium sit.[1] They are a family of glycoproteins that are an integral part of the structural scaffolding of basement membranes in almost every animal tissue. Laminins are secreted and incorporated into cell-associated extracellular matrices. They are shaped like a cross. The basal lamina (often erroneously called basement membrane) is a layer on which epithelium sits. ... Types of epithelium In biology and medicine, epithelium is a tissue composed of a layer of cells. ... A glycoprotein is a macromolecule composed of a protein and a carbohydrate (an oligosaccharide). ... In biology, extracellular matrix (ECM) is any material part of a tissue that is not part of any cell. ...

Contents

Types

Each laminin molecule is a heterotrimer assembled from alpha-, beta-, and gamma-chains.[2] In biochemistry, a trimer is a macromolecular compound formed by three non-covalently bound macromolecules. ...

  • There are five forms of alpha-chains: LAMA1, LAMA2, LAMA3, LAMA4, LAMA5
  • There are four of beta-chains: LAMB1, LAMB2, LAMB3, LAMB4
  • There are three of gamma-chains: LAMC1, LAMC2, LAMC3

Fifteen laminin trimers have been identified.


Networks

Laminins form independent networks and are associated with type IV collagen networks via entactin, and perlecan. They also bind to cell membranes through integrin receptors and other plasma membrane molecules, such as the dystroglycan glycoprotein complex and Lutheran blood group glycoprotein.[1] Through these interactions, laminins critically contribute to cell attachment and differentiation, cell shape and movement, maintenance of tissue phenotype, and promotion of tissue survival.[1][2] Some of these biological functions of laminin have been associated with specific amino-acid sequences or fragments of laminin.[1] For example, the peptide sequence [GTFALRGDNGDNGQ], which is located on the alpha-chain of laminin, promotes adhesion of endothelial cells.[3] Tropocollagen triple helix. ... Entactin : a component of the basement membrane along side other components such as collagen type IV, proteoglycans ( heparan sulphate and glycosaminoglycans), laminin and fibronectin. ... Perlecan is a large multidomain proteoglycan that binds to and cross-links many extracellualr matrix (ECM) components and cell-surface molecules. ... An integrin, or integrin receptor, is an integral membrane protein in the plasma membrane of cells. ... In biochemistry, a receptor is a protein on the cell membrane or within the cytoplasm or cell nucleus that binds to a specific molecule (a ligand), such as a neurotransmitter, hormone, or other substance, and initiates the cellular response to the ligand. ... Drawing of a cell membrane A component of every biological cell, the cell membrane (or plasma membrane) is a thin and structured bilayer of phospholipid and protein molecules that envelopes the cell. ... Dystroglycan is a protein of the cytoskeleton involved in joining dystrophin and laminin. ... Peptides (from the Greek πεπτος, digestible), are the family of short molecules formed from the linking, in a defined order, of various α-amino acids. ...


Pathology

Dysfunctional structure of one particular laminin, laminin-2, is the cause of some forms of muscular dystrophy. Laminin-2 is composed of an α2, a β1 and a γ1 chains. This laminin's distribution includes the brain and muscle fibers. In muscle, it binds to alpha dystroglycan via the G domain, and via the other end binds to the extracellular matrix. Progeria is the result of a defect in the prolaminin receptor that prevents the cleaving and activation of prolaminin into laminin. Muscular dystrophy refers to a group of genetic, hereditary muscle diseases that cause progressive muscle weakness. ... In biology, extracellular matrix (ECM) is any material part of a tissue that is not part of any cell. ... The term Progeria narrowly refers to Hutchinson-Gilford Progeria syndrome, but the term is also used more generally to describe any of the so-called accelerated aging diseases. The word progeria is derived from the Greek for prematurely old. Because the accelerated aging diseases display different aspects of aging, but...


References

  1. ^ a b c d M. A. Haralson and John R. Hassell (1995). Extracellular matrix: a practical approach. Ithaca, N.Y: IRL Press. ISBN 0-19-963220-0. 
  2. ^ a b Colognato H, Yurchenco P (2000). "Form and function: the laminin family of heterotrimers". Dev. Dyn. 218 (2): 213-34. PMID 10842354. 
  3. ^ Beck et al., 1999.

External links

  • The Laminin Protein
  • MeSH Laminin

  Results from FactBites:
 
Creating unique personal care products scientifically (608 words)
Laminin is a major component of basement membranes made by epithelial cells.
Laminin is composed of three different subunits in a cross-linked structure.
It is present in an insoluble form at the cell surface and in connective tissue and in a soluble form in plasma.
UWEB :: Research : Biomaterials Tutorial (455 words)
Laminin is a widely present protein that contributes to the formation of the extracellular matrix, particularly the basement membrane [1].
The laminin in basement membranes is actually produced by a wide variety of cells, and this protein appears to be involved in an equally wide variety of activities, including cell adhesion, migration and differentiation, embryonic development, and angiogenesis (blood vessel formation) during wound healing [1,2,3].
Laminin is of interest in the biomaterials field because of the possibility that coating a device with the protein may improve the host-device interface.
  More results at FactBites »

 
 

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