NCAM-180, the large isoform of the neural cell adhesion molecule of the mouse, is encoded by an alternatively spliced transcript.

The three different isoforms (NCAM-180, -140 and -120) of the murine neural cell adhesion molecule are encoded by a single gene. The two smaller isoforms, NCAM-120 and -140 are generated by alternative RNA splicing of the primary transcript. We here report sequence data of a mouse cDNA clone reverse transcribed from NCAM mRNA containing an extra fragment of 801 nt. This cytoplasmic domain of NCAM-140 and codes for additional 267 amino acids. We conclude that the sequence presented represents the 3' portion of the 7.4 kb NCAM transcript, which is also generated by alternative splicing. Thus, this sequence probably encodes NCAM-180, a polypeptide with a Mr of 117,181.