Nidogen-2: a new basement membrane protein with diverse binding properties.
Human nidogen-2 was cloned and sequenced (1375 residues) and found to share 46% sequence identity and a similar domain arrangement with the previously characterized basement membrane protein nidogen-1. Recombinant nidogen-2 was purified as a 200 kDa protein from transfected mammalian cell medium, showed a high level of N and O-glycosylation, and could be clearly distinguished from nidogen-1 (150 kDa) by specific antibodies. Electron microscopy demonstrated that the two isoforms have a similar shape, consisting of three globular domains connected by two threads, but differ somewhat in length. Northern blots and immunological assays demonstrated co-expression of the nidogens in various tissues and cultured cells. Immunofluoresence revealed colocalization in vessel walls and other basement membrane zones but some differences in heart and skeletal muscle. Nidogen-2 interacted with collagens I and IV, and perlecan at a comparable level to nidogen-1 but failed to bind to fibulins. Nidogen-2 bound to laminin-1, but only moderately to the epitope on the laminin gamma1 chain, which promotes high-affinity binding of nidogen-1. Both nidogens were cell-adhesive for a restricted number of cell lines, with nidogen-2 having a higher activity. Together, these data suggest that nidogen-2 can compensate for some but not all functional activities ascribed to nidogen-1.
Kohfeldt
E
E
Max-Planck-Institut für Biochemie, D-82152 Martinsried, Germany.
Sasaki
T
T
Göhring
W
W
Timpl
R
R
D000595:Amino Acid Sequence; D001483:Base Sequence; D001485:Basement Membrane / Q000737:chemistry*; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D015815:Cell Adhesion Molecules; D003001:Cloning, Molecular; D003094:Collagen / Q000378:metabolism; D005109:Extracellular Matrix; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D005688:Galactosamine / Q000032:analysis; D005944:Glucosamine / Q000032:analysis; D006801:Humans; D008024:Ligands; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D008969:Molecular Sequence Data; D011485:Protein Binding; D011498:Protein Precursors / Q000235:genetics; D021382:Protein Sorting Signals / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis; D017422:Sequence Analysis, DNA; D014018:Tissue Distribution
D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; D015815:Cell Adhesion Molecules; D016326:Extracellular Matrix Proteins; D008024:Ligands; D008562:Membrane Glycoproteins; C114729:NID2 protein, human; D011498:Protein Precursors; D021382:Protein Sorting Signals; D011994:Recombinant Proteins; C029967:nidogen; D005688:Galactosamine; D003094:Collagen; D005944:Glucosamine