Structural organization of the mouse neurochondrin gene

Neurochondrin is a brain and bone specific leucine-rich protein. We previously cloned the two types of mRNAs (neurochondrin-1; 729 amino acids and neurochondrin-2; 712 amino acids) from mouse and human species. As a first step, to better understand the mechanism of the bone and brain specific and developmentally regulated expression of the neruochondrin gene, the genomic organization of murine neurochondrin was determined. It consists of 7 exons and spans about 10 kb; all splice junctions conform to the GT/AG rule. It codes for two alternatively spliced messenger RNAs, neurochondrin-1 containing all 7 exons and neurochondrin-2 lacking exon 1b but containing the other exons. Cap site analysis showed that the major transcription initiation occurs at 765 bp upstream of the ATG start codon of neurochondrin-1. The promoter region has no TATA and CAAT box-like sequence but contains potential AP-1 and SP-1 binding sites. The neurochondrin gene is localized to mouse chromosome 4D1 and rat chromosome 5q36.11.