RAT DESMIN GENE STRUCTURE AND EXPRESSION

The isolation of two partial genomic clones and a near full length cDN A clone encoding the rat intermediate filament protein desmin is repor ted. Desmin is a differentiation marker for all types of muscle cells. The nucleotide order of the coding region and 0.1 kb of 5'-flanking s equences of the rat desmin gene has been determined. One genomic clone encompasses exons I-III and approx. 12 kb of 5'-flanking sequences, w hile the other clone contains exons VII-IX and about 12 kb of 3'-flank ing sequences. Northern analysis of RNA from different organs reveals that, as expected, desmin is expressed in striated, heart and smooth m uscle cells containing tissues; among other tissues, lung displays rel atively high expression levels, while desmin mRNA is barely detectable in spleen, kidney and liver. S1 mapping reveals that the same transcr iption initiation site is used in all desmin mRNA containing tissues.