Isolation of cDNA clones for the chicken neural cell adhesion molecule (N-CAM).

Abstract

Enriched mRNA coding for the neural cell adhesion molecule (N-CAM) was prepared from 9-day embryonic chicken brains by immunoprecipitation of polysomes with antibodies to N-CAM. This mRNA programmed the translation in vitro of N-CAM polypeptide chains in a rabbit reticulocyte lysate system. Two independent N-CAM c[complementary]DNA clones (designated pEC001 ad pEC020) were derived from the enriched RNA. The specificity of pEC001 for N-CAM mRNA was verified by hybrid selection experiments. Both plasmids hybridized to 2 discrete 6-7-kilobase-long RNA species in poly(A)+ RNA from embryonic chicken brain and to lesser amounts of polydisperse material of smaller sizes (probably degradation products of the large RNA). No hybridization was detected to poly(A)+ RNA from embryonic liver. Southern blotting experiments with pEC001 detected only 1 hybridizing fragment in chicken genomic DNA digested with several different restriction enzymes, suggesting that sequences corresponding to those within this region of N-CAM mRNA are present at most only a few times, and possibly only once, in the chicken genome.