title: Alternative splicing of a Drosophila tropomyosin gene generates muscle tropomyosin isoforms with different carboxy-terminal ends.
abstract: The muscle tropomyosin I (mTm I) gene from Drosophila melanogaster has been analyzed and shown to express a complex transcription unit consisting of two sets of tissue-specific mRNAs. A 1.3- and 1.6-kilobase set of mRNAs is expressed during myogenesis in embryos, and in myogenic cell cultures. The mRNAs encode a 34,000-dalton muscle tropomyosin isoform. The same mTm I gene expresses a different set of 1.7- and 1.9-kilobase mRNAs in thoracic flight muscle tissue of the adult. The thorax RNAs encode a new tropomyosin isoform resolved on two-dimensional gels. The structure of the gene has been determined, and we show that the embryonic and thoracic mRNAs are generated by alternative splicing. The alternate exon splicing patterns determine a different 27 amino acids at the carboxy-terminal end of the two tropomyosin isoforms. These results show that the carboxy-terminal domain of tropomyosin is highly regulated in determining tropomyosin function. The results also show that contractile protein isoforms can be generated by single as well as multiple genes.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D004262:DNA Restriction Enzymes / Q000378:metabolism; D004331:Drosophila melanogaster; D004591:Electrophoresis, Polyacrylamide Gel; D005786:Gene Expression Regulation; D012326:RNA Splicing; D012333:RNA, Messenger / Q000032:analysis; D014335:Tropomyosin / Q000235:genetics*
chemical_list: D012333:RNA, Messenger; D014335:Tropomyosin; D004262:DNA Restriction Enzymes