Binding properties of the neural cell adhesion molecule to different components of the extracellular matrix.
A soluble form of the neural cell adhesion molecule (N-CAM) was obtained from 100,000-g supernatants of crude brain membrane fractions by incubation for 2 h at 37 degrees C. The isolated N-CAM, consisting of one polypeptide chain with a molecular mass of 110 kilodaltons (N-CAM 110), was studied for its binding specificity to different components of the extracellular matrix (ECM). N-CAM 110 bound to different types of collagen (collagen types I-VI and IX). The binding efficiency was dependent on salt concentration and could be called specific according to the following criteria: (a) Binding showed substrate specificity (binding to collagens, but not to other ECM components, such as laminin or fibronectin). (b) Binding of N-CAM 110 to heat-denatured collagens was absent or substantially reduced. (c) Binding was saturable (Scatchard plot analyses were linear with KD values in the range of 9.3-2.0 X 10(-9) M, depending on the collagen type and buffer conditions). Binding of N-CAM 110 to collagens could be prevented in a concentration-dependent manner by the glycosaminoglycans heparin and chondroitin sulfate. N-CAM 110 also interacted with immobilized heparin, and this interaction could be prevented by heparin and chondroitin sulfate. Thus, in addition to its role in cell-cell adhesion, N-CAM is a binding partner for different ECM components, an observation suggesting that it also serves as a substrate adhesion molecule in vivo.
Probstmeier
R
R
Department of Neurobiology, University of Heidelberg, F.R.G.
Kühn
K
K
Schachner
M
M
D000818:Animals; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism*; D015815:Cell Adhesion Molecules / Q000302:isolation & purification / Q000378:metabolism*; D003094:Collagen / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005109:Extracellular Matrix / Q000378:metabolism*; D006493:Heparin / Q000378:metabolism; D007700:Kinetics; D051379:Mice; D008970:Molecular Weight; D011485:Protein Binding; D011869:Radioligand Assay
D015815:Cell Adhesion Molecules; D006493:Heparin; D003094:Collagen