Tropomyosin gene Splicing

Wieczorek, D.E, Smith, C.W. and Nadal-Ginard, B. The rat alpha-tropomyosin gene generates a minimum of six different mRNAs coding for striated, smooth, and nonmuscle isoforms by alternative splicing (1988) Mol. Cell Biol. 8, 679-94... 

Ruiz-Opazo, N., and Nadal-Ginard, B. (1987). Alpha-tropomyosin gene organization. Alternative splicing of duplicated iso type-specific exons accounts for the production of smooth and striated muscle isoforms./. Biol. Chem. 262, 4755—4765. 

Fleenor, D.E, Hickman, KH., Lindquester, G.]. Devlin, R.B. (1992). Avian cardiac tropomyosin gene produces tissue-specific isoforms through alternative RNA splicing.. Musde Res. Cell Motility, 13, 55-63. 

Libri, D., Piseri, A. 8e Fiszman, M.Y. (1991). Tissue-specific splicing in vivo of the -tropomyosin gene-dependence on an RNA secondary structure. Scietux, 252, 1842-5. 

Fig. 1.48. Differential splicing in muscle proteins, a) The troponin gene of rats possess 18 exons that encode 258 amino acids. Different subtypes of troponin are found in various types of muscle tissue.The exons 1-3 and 9-15 are found in aU subtypes, while the exons 4-8 appear in various combinations, allowing 32 possible combinations. Exon 16 or 17 are found in every subtype. Altogether, 64 different mRNAs can be formed from the troponin pre-mRNA. After Breitbart and Nadal-Grinard (1986). b) Tropomyosin is a muscle protein that can be alternatively spliced in different muscle tissue. Shown in the figure are the predominant subtypes for striated and smooth muscle. After Wieczorek et al., 1989.

The possibilities for alternative splicing are enormous. One particularly elaborate example is seen in the gene for tropomyosin in vertebrates. Recall that tropomyosin is a key component of vertebrate striated muscle (see fig. 5.18). The mRNA for tropomyosin found in striated muscle undergoes nine splices in the process of maturation (fig. 31.22). Variants of tropomyosin resulting from alternative splicing are found in other tissues of the same organism. It seems likely... 

Similarly, multiple genes, alternative RNA splicing, and posttranslational modifications result in multiple essential and regulatory light chains, tropomyosins, titins, and other myofibrillar proteins. Energy pathway enzymes are differentially expressed in various skeletal fiber types, in cardiac and smooth muscle, and at different stages of development. This also applies to Ca regulatory proteins such as the... 

Tropomyosin Binds actin in thin filament a, 34 kDa P. 36 kDa 4 classes fast a, slow a, P and platelet-like but many more transcripts >4 genes gene duplicahon plus mainly alternative splicing Regulation of contraction... 

Fig. 9.11. Alternative splicing of tropomyosin 1 gene showing alternative transcripts produced in different tissues (Forryschaudies Hughes, 1991). The solid boxes are exons transcribed in all tissues, others are alternatively spliced. The lines represent introns.

Forryschaudies, S. Hughes, S.H. (1991). The chicken tropomyosin-1 gene generates 9 messenger-RNAs by alternative splicing. J. Biol. Chem., 266, 13821—7. 

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