Human NB-2 of the contactin subgroup molecules: Chromosomal localization of the gene (CNTN5) and distinct expression pattern from other subgroup members

NB-2 is one of the neural recognition molecules in the contactin subgroup, which belongs to the immunoglobulin superfamily, In rat, the six molecules in this subgroup that have been reported to date are contactin, TAG-1, BIG- 1, BIG-2, NB-2, and NB-3, We have isolated cDNAs encoding the two splicing isoforms of human NB-2, The long isoform of human NB-2 consists of 1100 ami no acids residues that are 91% homologous to rat NB-2 at the amino acid seq uence level. The short isoform lacks 74 amino acid residues between residue s 19 and 93 of the long isoform, Among various regions of the adult human b rain, high-level expression of NB-2 was detected in the amygdala and occipi tal lobe, whereas expression was low in the corpus callosum, caudate nucleu s, and spinal cord. Although there were some differences, the expression pa ttern of NB-2 was the most similar to that of BIG-1 in the brain, Likewise, contactin and BIG-2 exhibited similar expression patterns. The expression of TAG-1 showed the least regional differences. The human NB-2 gene (CNTN5) was mapped to chromosome 11q21-q22.2 by fluorescence in situ hybridization , Our results suggest that the NB-2 gene may contribute to human neurologic al disorders, (C) 2000 Academic Press.