Targeting of cardiac muscle titin fragments to the Z-bands and dense bodies of living muscle and non-muscle cells
✍ Scribed by Ayoob, Joseph C. ;Turnacioglu, Kenan K. ;Mittal, Balraj ;Sanger, Jean M. ;Sanger, Joseph W.
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 1007 KB
- Volume
- 45
- Category
- Article
- ISSN
- 0886-1544
No coin nor oath required. For personal study only.
✦ Synopsis
A 6.5-kb N-terminal region of embryonic chick cardiac titin, including the region previously reported as part of the protein zeugmatin, has been sequenced, further demonstrating that zeugmatin is part of the N-terminal region of titin, and not a separate Z-band protein. This Z-band region of cardiac titin, from both 7-and 19-day embryos as well as from adult animals, was found to contain six different small motifs, termed z-repeats [Gautel et al., 1996: J. Cell Sci. 109:2747-2754], of approximately 45 amino acids each sandwiched between flanking regions containing Ig domains. Fragments of Z-band titin, linked to GFP, were expressed in cultured cardiomyocytes to determine which regions were responsible for Z-band targeting. Transfections of primary cultures of embryonic chick cardiomyocytes demonstrated that the z-repeats play the major role in targeting titin fragments to the Z-band. Similar transfections of skeletal myotubes and non-muscle cells lead to the localization of these cardiac z-repeats in the Z-bands of the myofibrils and the dense bodies of the stress fibers. Over-expression of these z-repeat constructs in either muscle or non-muscle cells lead to the loss of the myofibrils or stress fibers, respectively. The transfection experiments also indicated that small domains of a protein, 40 to 50 amino acids, can be studied for their localization properties in living cells if a suitable linker is placed between these small domains and the much larger 28 kDa GFP protein. Cell Motil.