Laminin is the major non-collagenous component of the basal lamina, such as those on which cells of an epithelium sit. The basal lamina is a layer of extracellular matrix on which Epithelium sits and which is secreted by the epithelial cells In biology and medicine epithelium is a tissue composed of cells that line the cavities and surfaces of structures throughout the body [1] Basically, laminin is a protein found in the "extracellular matrix", the sheets of protein that form the substrate of all internal organs also called the "basement membrane". It has four arms that can bind to four other molecules. The three shorter arms are particularly good at binding to other laminin molecules, which is what makes it so great at forming sheets. The long arm is capable of binding to cells, which helps anchor the actual organs to the membrane.
The laminin protein is made up of three separate parts, called the A, B1, and B2 chains. That gives it a total of six "ends", which accounts for a lot of its flexibility in connecting up various kinds of molecules. Because of this, scientists who create biomaterials are extremely interested in the whole family of laminins. They are a family of glycoproteins that are an integral part of the structural scaffolding in almost every animal tissue. Not to be confused with Peptidoglycan. Glycoproteins are proteins that contain Oligosaccharide chains ( Glycans) covalently attached Laminins are secreted and incorporated into cell-associated extracellular matrices. In Biology, the extracellular matrix ( ECM) is the Extracellular part of animal tissue that usually provides structural support to the cells
Laminin is vital to making sure overall body structures hold together. Improper production of laminin can cause muscles to form improperly, leading to a form of muscular dystrophy. Muscular dystrophy (MD refers to a group of genetic, Hereditary Muscle diseases that cause progressive muscle weakness It can also cause progeria. Progeria is a condition of early aging which usually refers specifically to Hutchinson-Gilford Progeria syndrome.
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Types
Each laminin molecule is a heterotrimer assembled from alpha-, beta-, and gamma-chains. In Biochemistry, a trimer is a macromolecular complex formed by three usually non-covalently bound, Macromolecules like Proteins or [2]
Fifteen laminin trimers have been identified. Laminin alpha 1, also known as LAMA1, is a human Gene. Laminin alpha 2 (merosin congenital muscular dystrophy, also known as LAMA2, is a human Gene. Laminin alpha 3, also known as LAMA3, is a human Gene. Laminin alpha 4, also known as LAMA4, is a human Gene. Laminin alpha 5, also known as LAMA5, is a human Gene. Laminin beta 1, also known as LAMB1, is a human Gene. Laminin beta 2 (laminin S, also known as LAMB2, is a human Gene. Laminin beta 3, also known as LAMB3, is a human Gene. Laminin gamma 1 (formerly LAMB2, also known as LAMC1, is a human Gene. Laminin gamma 2, also known as LAMC2, is a human Gene.
Networks
Laminins form independent networks and are associated with type IV collagen networks via entactin, and perlecan. Collagen is the main Protein of Connective tissue in Animals and the most abundant protein in Mammals making up about 50% of the whole-body protein Entactin (or nidogen) is a component of the Basement membrane alongside other components such as Collagen type IV Proteoglycans ( heparan sulfate Heparan sulfate proteoglycan 2 ( HSPG2) is a human Gene which encodes the perlecan Protein. 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. Integrins are Cell surface receptors that interact with the Extracellular matrix (ECM and mediate various intracellular signals. In Biochemistry, a receptor is a Protein molecule embedded in either the Plasma membrane or Cytoplasm of a cell to which a mobile signaling The cell membrane (also called the plasma membrane, plasmalemma, or "phospholipid bilayer" is a Selectively permeable Lipid bilayer Dystroglycan 1 (dystrophin-associated glycoprotein 1, also known [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. Peptides (from the Greek πεπτίδια, "small digestibles" are short Polymers formed from the linking in a defined order of α- Amino [3]
Pathology
Dysfunctional structure of one particular laminin, laminin-2, is the cause of one form of congenital muscular dystrophy[4]. Congenital muscular dystrophy ( CMD) is the term used to describe Muscular dystrophy that is present at birth 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 and integrin alpha7-beta1 via the G domain, and via the other end binds to the extracellular matrix. Integrins are Cell surface receptors that interact with the Extracellular matrix (ECM and mediate various intracellular signals. In Biology, the extracellular matrix ( ECM) is the Extracellular part of animal tissue that usually provides structural support to the cells
References
- ^ 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.
- ^ a b Colognato H, Yurchenco P (2000). "Form and function: the laminin family of heterotrimers". Dev. Dyn. 218 (2): 213–34. doi:. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document. PMID 10842354.
- ^ Beck et al. , 1999.
- ^ Hall, TE et al (2007). Proc Natl Acad Sci USA 104 (17), 7092-7097 doi: 10. 1073/pnas. 0700942104
External links
Medical Subject Headings ( MeSH) is a huge Controlled vocabulary (or metadata system for the purpose of indexing journal articles and booksDictionary
laminin
-noun
- (biochemistry) Any of a class of glycoproteins found in the basement membranes of most animal tissue
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