IDENTIFICATION OF CORTEXIN - A NOVEL, NEURON-SPECIFIC, 82-RESIDUE MEMBRANE-PROTEIN ENRICHED IN RODENT CEREBRAL-CORTEX

Nucleotide sequence analysis of a cDNA clone of a rat cortex-enriched mRNA identifies a novel integral membrane protein of 82 amino acids. T he encoded protein is named cortexin to reflect its enriched expressio n in cortex. The amino acid sequence of rat cortexin and its mouse hom ologue are nearly identical (98% similarity), and both contain a conse rved single membrane-spanning region in the middle cf each sequence. N orthern blot analysis shows that cortexin mRNA is brain-specific, cort ex-enriched, and present at significant levels in fetal brain, with pe ak expression in postnatal rodent brain. In situ hybridization studies detect cortexin mRNA primarily in neurons of rodent cerebral cortex, but not in cells of the hindbrain or white matter regions. The functio n of cortexin may be particularly important to neurons of both the dev eloping and adult cerebral cortex.