Molecular cloning of cDNA encoding the rat neural cell adhesion molecule L1. Two L1 isoforms in the cytoplasmic region are produced by differential splicing.

We have isolated and sequenced a full-length cDNA encoding the rat neural cell adhesion molecule L1. The deduced amino acid sequence as a whole shows high homology to mouse L1 sequence. In addition to this complete form of L1, we found an isoform, L1cs, which lacks four amino acid residues (RSLE) in the cytoplasmic domain and probably is derived from the same single L1 gene by tissue-specific alternative splicing. While L1 mRNA was predominantly expressed in the brain, L1cs mRNA was found exclusively in peripheral nervous tissue. Differential splicing in the highly conserved cytoplasmic domain may play an important role in modulating the function of L1 in different cells.