2) NrCAM NrCAM encodes a single-transmembrane-domain cell adhesion molecule with six immunoglobulin domains, four to five fibronectin III repeats, a transmembrane domain and a C-terminal cytoplasmic domain with tyrosine kinase phosphoacceptor sites [225]. Multiple NrCAM isoforms can be identified as the products of differential RNA splicing events which produce NrCAM translation products that contain short inserted peptide sequences. NrCAM mRNA expression is high in hippocampus, mid- to deep layers of the cerebral cortex, cerebellum purkinge cell layers and striatal interneurons. Cells of the substantia nigra and ventral tegmental area (VTA) express hybridization densities that are almost as dense as those identified in hippocampal pyramidal neurons [131]. Many, but not all of the NrCAM immunopositive neurons in the VTA also express dopamine transporter (DAT) immunoreactivity, a marker for dopaminergic neurons [131].
