Developmental study of detergent solubility and polypeptide composition of the neural cell adhesion molecule.

The neural cell adhesion molecule (N-CAM), a glycoprotein synthesized by neurons, glial cells and muscle cells, is involved in cell-cell adhesion. In this report we describe developmental changes in the amount of N-CAM polypeptides in rat forebrain and in detergent solubility of N-CAM. The amount of N-CAM changed during development with a peak in early postnatal life. N-CAM was composed of the following polypeptides: HMr (molecular weight between 250,000 and 350,000 daltons), A (200,000 daltons), B (135,000 daltons) and C (115,000 daltons). In embryonic life N-CAM consisted of 10% HMr, 26% A, 53% B and 11% C. During development only the relative amount of polypeptide C increased significantly, from 11% at embryonic day 17 to 22% at postnatal day 4. Postnatally the polypeptide composition of N-CAM did not change. No Triton X-100 insoluble N-CAM was observed in early development, but at postnatal day 40 14% of N-CAM was Triton X-100 insoluble. This fraction was shown to consist of polypeptide C.