Four fibroblast tropomyosin isoforms are expressed from the rat alpha-tropomyosin gene via alternative RNA splicing and the use of two promoters

Goodwin, L. O., Lees-Miller, J. P., Leonard, M. A., Cheley, S. B., Helfman, D. M. (May 1991) Four fibroblast tropomyosin isoforms are expressed from the rat alpha-tropomyosin gene via alternative RNA splicing and the use of two promoters. J Biol Chem, 266 (13). pp. 8408-15. ISSN 0021-9258 (Print)0021-9258 (Linking)

URL: http://www.ncbi.nlm.nih.gov/pubmed/2022655

Abstract

cDNA clones encoding four rat tropomyosin isoforms, termed TM-2, TM-3, TM-5a, and TM-5b, were isolated and characterized. All are derived from the alpha-tropomyosin gene via alternative RNA processing and the use of two alternate promoters. The cDNA sequences predict that TM-2 and TM-3 both contain 284 amino acids and differ from each other only at an internal region of the protein from amino acids 189 through 213, due to alternative splicing of exons 6a and 6b. TM-5a and TM-5b both contain 248 amino acids and differ from each other only at an internal exon encoding amino acids 153 through 177, also due to alternative splicing of exons 6a and 6b. The differences in the amino acid sequence encoded by these alternate exons affects the theoretical actin-binding pattern of the tropomyosins, such that TM-5b is expected to bind actin with greater affinity than TM-5a. TM-2 and TM-3 are transcribed from the upstream promoter, and TM-5a and TM-5b are transcribed from an internal promoter. In addition, all four isoforms contain the identical COOH-terminal coding region. RNA protection analyses revealed that the mRNA for each isoform is expressed in a number of different tissues and cell types, although the expression of some isoforms is restricted to particular cell types. Furthermore, the expression of mRNA encoding these isoforms was found to be altered in a number of different virally transformed cell lines. The changes in the expression of tropomyosin mRNAs in transformed cells reflect changes in the relative use of the two promoters, as well as the relative use of alternatively spliced exons 6a and 6b.

Item Type: Paper
Uncontrolled Keywords: Actins/metabolism Amino Acid Sequence Animals Antisense Elements (Genetics) Base Sequence Cell Line Cloning, Molecular Dna Exons Fibroblasts/metabolism Molecular Sequence Data Organ Specificity/genetics *Promoter Regions, Genetic *RNA Splicing Rats Restriction Mapping Sequence Alignment Tropomyosin/*genetics/metabolism
Subjects: bioinformatics > genomics and proteomics > genetics & nucleic acid processing > DNA, RNA structure, function, modification > Alternative Splicing
organs, tissues, organelles, cell types and functions > cell types and functions > cell types > fibroblasts
organs, tissues, organelles, cell types and functions > cell types and functions > cell types > fibroblasts
organs, tissues, organelles, cell types and functions > cell types and functions > cell types > fibroblasts

bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > tropomyosin
CSHL Authors:
Communities: CSHL labs > Helfman lab
Depositing User: Matt Covey
Date: 5 May 1991
Date Deposited: 07 Jan 2016 15:23
Last Modified: 07 Jan 2016 15:23
Related URLs:
URI: http://repository.cshl.edu/id/eprint/32078

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