Abstract
: 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°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 fi‐bronectin). (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 ± 10−9M, depending on ihe 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