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.

Contents

Types

Each laminin molecule is a heterotrimer assembled from alpha-, beta-, and gamma-chains.[2]

  • 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 peptide sequence [GTFALRGDNGDNGQ], which is located on the alpha-chain of laminin, promotes adhesion of endothelial cells.[3]

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.

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.
 
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