The laminins are collagen-like glycoproteins and a component of the extracellular matrix . Laminins are found in all basal laminae , and they have binding sites for cell surface receptors. Together with type IV collagen , entactin (Nidogen) and the heparan sulfate proteoglycan Perlecan , the laminins form the basement membranes mentioned. Other important components of the basal lamina are fibronectin and a number of other proteoglycans.
Fifteen laminini isoforms are known to date. These are tissue-specifically distributed in the animal organism. The laminin molecule consists of an α-, a β- and a γ- protein chain , which are composed in heterotrimeric form to the respective laminin molecule. It should be noted that 5 different α chains, 3 different β chains and 3 different γ chains have been detected so far.
The following combinations of protein chains in the laminin isoforms have so far been discovered:
- Laminin -1: α1β1γ1 (Laminin-111)
- Laminin -2: α2β1γ1 (Laminin-211)
- Laminin -3: α1β2γ1 (Laminin-121)
- Laminin -4: α2β2γ1 (Laminin-221)
- Laminin -5: α3β3γ2 (Laminin-332)
- Laminin -6: α3β1γ1 (Laminin-311)
- Laminin -7: α3β2γ1 (Laminin-321)
- Laminin -8: α4β1γ1 (Laminin-411)
- Laminin -9: α4β2γ1 (Laminin-421)
- Laminin -10: α5β1γ1 (Laminin-511)
- Laminin -11: α5β2γ1 (Laminin-521)
- Laminin -12: α2β1γ3 (Laminin-231)
- Laminin -13: α3β2γ3 (Laminin-323)
- Laminin -14: α4β2γ3 (Laminin-423)
- Laminin -15: α5β2γ3 (Laminin-523)
- Timpl R , Martin GR, Bruckner P, Wick G, Wiedemann H .: Nature of the collagenous protein in a tumor basement membrane. . In: Eur J Biochem . . 84, No. 1, March 1978, pp. 43-52. PMID 648517 .
- Aumailley M, Bruckner-Tuderman L, Carter WG, et al. : A simplified laminin nomenclature . In: Matrix Biol. . 24, No. 5, August 2005, pp. 326-32. doi : 10.1016 / j.matbio.2005.05.006 . PMID 15979864 .