Identification of a human brain-specific gene, calneuron 1, a new member of the calmodulin superfamily

The calmodulin superfamily includes the calmodulins, calcium-binding proteins, and related genes. Herein, we describe the cloning and characterization of human calneuron 1 (CALN1). CALN1 encodes a novel neuron-specific protein that maps to chromosome 7q11. CALN1 spans a large genomic region (>360 kb). Sequence comparison shows significant similarity with the calmodulin superfamily of genes, especially in the two conserved EF-hand motifs. The mouse orthologous gene (Caln1) shows little prenatal expression, with highest expression at Postnatal Day 21. In situ hybridization to adult mouse brain shows high expression in the cerebellum, hippocampus, and cortex. The high expression of this gene exclusively in brain, the developmental changes in expression levels, the high homology with calmodulin which indicates a potential role in signal transduction, and the cellular localization of the mRNA suggest that CALN1 has a significant role in the physiology of neurons and is potentially important in memory and learning.