Titin and Nebulin: Giant Multitasking Protein Rulers in Muscle

Wang, K.

doi:10.1007/978-3-642-79482-7_11

Cited by 2 publications

(1 citation statement)

References 61 publications

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“…Titin filaments extending from the opposing Z-bands of a sarcomere, thus, anchor the myosin filaments, keeping them centered despite changes in sarcomere length that occur during contraction. In addition, titin is also thought to be responsible for the passive resistance of sarcomeres to stretching [Maruyama et al, 1977;Wang, 1994;Horowits and Podolsky, 1987].…”

Section: Introductionmentioning

confidence: 99%

Targeting of cardiac muscle titin fragments to the Z-bands and dense bodies of living muscle and non-muscle cells

Ayoob

Turnacioglu

Mittal

et al. 2000

Cell Motil. Cytoskeleton

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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.

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Section: Introductionmentioning

confidence: 99%

Targeting of cardiac muscle titin fragments to the Z-bands and dense bodies of living muscle and non-muscle cells

Ayoob

Turnacioglu

Mittal

et al. 2000

Cell Motil. Cytoskeleton

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Zeugmatin is Part of the Z-band Targeting Region of Titin.

Turnacioglu

Mittal

Dabiri

et al. 1997

Cell Struct. Funct.

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ABSTRACT. Originally, zeugmatin was identified as a 600-800 kD muscle specific protein in Z-bands of cardiac and skeletal muscles by Maher et ah (1985). In this presentation we review our work on myofibrillogenesis and present evidence that zeugmatin is actually part of the Z-Band region of titin and that this region of titin plays an important role in the assembly of the Z-bands and myofibrils. Rhee et al. (1994) reported that during myofibrillogenesis, zeugmatin antibody localization is detected in fully formed Z-bands in the mature myofibrils, in the Z-bodies of the nascent myofibrils, but not in the Z-bodies of the premyofibrils. These observations lead to the suggestion that zeugmatin might be responsible for the fusion of the Z-bodies to form the solid Zbands of the mature myofibrils (Rhee et al. 1994). As part of a study to test aspects of this model of myofibrillogenesis, we isolated a 1.8 kb CDNAfrom a chicken cardiac expression library using an anti-zeugmatin antibody (Turnacioglu et al. , 1996). We found this chicken CDNAto be 60%identical at the amino acid level to a segment of the Z-band region of human cardiac titin (connectin) sequenced by Labeit and Kolmerer (1995). This homology along with Western blot analysis with purified titin, suggested that zeugmatin is in fact part of the N-terminal region of chicken titin. Whenexpressed in non-muscle cells, Zl.l product colocalized with the alpha-actinin in stress fiber dense bodies and focal adhesions. Cultures of non-muscle cells, skeletal myotubes and cardiomyocytes were also transfected with a fusion construct (Z1.1GFP) consisting of the Zl.l kb CDNAlinked to the CDNAfor green fluorescent protein (GFP). The Zl.l kb CDNAencodes only 362 of the approximately 2,000 amino acids which comprise the Z-band region of titin; neverthelss, the Z1.1GFPfusion protein targets in vivo to the alpha-actinin rich Z-bands of contracting myofibrils. A dominant negative phenotype was observed in living cells expressing highlevels of this Z1.1GFPfusion protein with inhibition of myofibrillogenesis as well as the disassembly of preexisting myofibrils in these cells. These data indicate that the Z-band region of titin (connectin) plays an important role in organizing and maintaining the structure of the myofibril.

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Titin and Nebulin: Giant Multitasking Protein Rulers in Muscle

Cited by 2 publications

References 61 publications

Targeting of cardiac muscle titin fragments to the Z-bands and dense bodies of living muscle and non-muscle cells

Targeting of cardiac muscle titin fragments to the Z-bands and dense bodies of living muscle and non-muscle cells

Zeugmatin is Part of the Z-band Targeting Region of Titin.

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