STRUCTURE AND EXPRESSION OF THE GENE ENCODING MURINE M-PROTEIN, A SARCOMERE-SPECIFIC MEMBER OF THE IMMUNOGLOBULIN SUPERFAMILY

The complete exon-intron organization of the murine gene encoding M-pr otein, a structural protein of sarcomeric myofibrils, was determined. The gene is composed of 37 exons and 36 introns, spanning similar to 7 5 kb of DNA. Intron positions are related to the modular structure of M-protein, which is composed essentially of immunoglobulin and fibrone ctin type III domains. Almost all repeats follow a two exon-one domain structure. The beginning and end of each domain are defined by intron s in phase I; internal introns are more divergent in position and very rarely use phase I. A single transcriptional start point was detected in both skeletal and cardiac muscle. Analysis of the prospective prom oter region revealed several potential regulatory elements. CAT expres sion assays using prometer deletion constructs identified three region s that seem to be most important for the muscle-specific transcription activation of the M-protein gene. These results provide the first com plete characterization of a gene for a member of the intracellular bra nch of the immunoglobulin superfamily. (C) 1998 Academic Press.