Still more complexity in mammalian basement membranes.
At the epithelial/mesenchymal interface of most tissues lies the basement membrane (BM). These thin sheets of highly specialized extracellular matrix vary in composition in a tissue-specific manner, and during development and repair. For about two decades it has been apparent that all BMs contain laminins, entactin-1/nidogen-1, Type IV collagen, and proteoglycans. However, within the past few years this complexity has increased as new components are described. The entactin/nidogen (E/N) family has expanded with the recent description of a new isoform, E/N-2/osteonidogen. Agrin and Type XVIII collagen have been reclassified as heparan sulfate proteoglycans (HSPGs), expanding the repertoire of HSPGs in the BM. The laminin family has become more diverse as new alpha-chains have been characterized, increasing the number of laminin isoforms. Interactions between BM components are now appreciated to be regulated through multiple, mostly domain-specific mechanisms. Understanding the functions of individual BM components and their assembly into macromolecular complexes is a considerable challenge that may increase as further BM and cell surface ligands are discovered for these proteins.
Erickson
A C
AC
Department of Cell Biology and Cell Adhesion and Matrix Research Center, University of Alabama at Birmingham, Birmingham, Alabama 35294-0019, USA.
Couchman
J R
JR
D018171:Agrin / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D001485:Basement Membrane / Q000737:chemistry / Q000378:metabolism*; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism; D015815:Cell Adhesion Molecules; D003094:Collagen / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D007797:Laminin / Q000737:chemistry / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000378:metabolism; D064828:Prolyl Hydroxylases; D011509:Proteoglycans / Q000737:chemistry / Q000378:metabolism
D018171:Agrin; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; D015815:Cell Adhesion Molecules; D007797:Laminin; C485658:Lepre1 protein, mouse; D008562:Membrane Glycoproteins; C114729:NID2 protein, human; C112846:Nid2 protein, mouse; D011509:Proteoglycans; D003094:Collagen; D064828:Prolyl Hydroxylases; C485657:P3H1 protein, human