Laminin, glomerular basement membrane

The glomerular basement membrane (GBM) forms the backbone of the glomerular tuft. It is composed of three layers lamina rara interna, lamina densa, and lamina rara externa. The glomerular basement membrane is composed of a network of collagen type IV molecules (H5) intertwined with nidogen to another network composed of molecules of laminin. Type IV collagen and laminin are responsible for the firmness of the glomerular basement membrane and enable adhesion of endothelial cells and podocytes as well. 

Laminin [consisting of three polypeptide chains, A, Bl (possibly replaced in GBM by S) and B2] is the most important noncollagenous protein of the glomerular basement membrane. Laminin forms a second network, which is connected to the collagen IV network probably via another protein called entactin or nidogen. Laminin is probably very important for cellular differentiation and adhesion, but its mesh clearly also contributes to the structure of the glomerular basement membrane. The postnatally common embryonic laminin-10 isoform is... 

Cell attachment to the glomerular basement membrane is mediated by laminin, entactin, and fibronectin, at least partly through integrin receptors on the cell surface of both endothelial and visceral epithelial cells. 

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