CDNA CLONING, GENOMIC ORGANIZATION, AND EXPRESSION OF THE HUMAN RTN2 GENE, A MEMBER OF A GENE FAMILY ENCODING RETICULONS

This paper describes the cDNA cloning, genomic organization, and expre ssion of the human RTN2 gene on chromosome 19q13.3, which was recogniz ed by virtue of its high similarity with the human RTN1 (formerly call ed NSP) gene on chromosome 14q21-q22. In a region of about 12 kb in to tal, 11RTN2 exons could be identified. Like the RTN1 gene, the RTN2 ge ne is transcribed into different mRNA variants. Two have a size of abo ut 2.3 kb, and a third has a size of about 1.3 kb. The two 2.3-kb tran scripts differ because of alternative splicing of exon 5. Transcriptio n of the 1.3-kb transcript starts presumably from an internal promoter within exon 5. The three mRNAs encode three different proteins, RTN2- A (545 aa), RTN2-B (472 aa), and RTN2-C (205 aa), which share a common carboxyterminal segment of 201 aa. In this common segment, the homolo gy with the RTN1 proteins, with yet unknown function, is found. Two hy drophobic subregions are present, which are thought to be responsible for the association of the RTN1 and RTN2 proteins with the endoplasmic reticulum. The amino-terminal regions of the RTN2-A and RTN2-B protei ns are rich in negatively charged residues and in proline and serine r esidues and contain multiple potential phosphorylation sites. Analysis of the expression of the RTN2 gene shows differential expression in h uman tissues with a strikingly high expression of the 1.3-kb transcrip t in Skeletal muscle. (C) 1998 Academic Press.