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RESEARCH ARTICLE |
Laboratory of Muscle Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, USA
*Author for correspondence (e-mail: horowits{at}helix.nih.gov)
Accepted August 11, 2001
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SUMMARY |
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-actinin at cell contacts. Each of the N-RAP constructs could inhibit the formation of mature myofibrils in cultured cardiomyocytes, with the effects of N-RAP-SR and N-RAP-IB depending on the time of transfection. The results show that each region of N-RAP is crucial for myofibril assembly. Combining the targeting and functional effects of N-RAP domains with information in the literature, we propose a new model for initiation of myofibrillogenesis.
Key words: Chick, Cardiomyocyte, N-RAP, LIM protein, Myofibril assembly
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INTRODUCTION |
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TopSUMMARYINTRODUCTIONMaterials and MethodsRESULTSDISCUSSIONREFERENCES |
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Immunofluorescent localization of N-RAP in cultured chick cardiomyocytes was consistent with this hypothesis, showing that N-RAP is found concentrated at the terminal ends of mature cells and at sites of cell to cell contact (Carroll and Horowits, 2000). In addition, N-RAP was found localized along myofibril precursors in immature cardiomyocytes (Carroll and Horowits, 2000). As cardiomyocytes spread in culture, immature fibrils containing punctate -actinin Z-bodies, -actin and muscle tropomyosin are formed (Dabiri et al., 1997; Dlugosz et al., 1984; Handel et al., 1991; Rhee et al., 1994; Schultheiss et al., 1990; Wang et al., 1988). This process appears to originate at the periphery of the cell, with the earliest myofibril precursors, the premyofibrils, containing nonmuscle myosin IIb (Rhee et al., 1994) and N-RAP (Carroll and Horowits, 2000). Time-lapse studies of living cardiomyocytes expressing -actinin fused to GFP suggest that the closely spaced -actinin beads in these structures aggregate laterally to form nascent myofibrils (Dabiri et al., 1997). The nascent myofibrils incorporate titin, and muscle myosin gradually replaces the nonmuscle isoform (Dabiri et al., 1997). The muscle myosin may exist as preformed bipolar thick filaments that are oriented and incorporated into the nascent myofibrils by their interactions with titin filaments (Holtzer et al., 1997; Schultheiss et al., 1990). Like nonmuscle myosin IIb, N-RAP is present in all of the myofibril precursors, but is not found in the mature sarcomeres (Carroll and Horowits, 2000).
In this study, we extend our investigation of N-RAP to the unique targeting and functional roles of the individual N-RAP domains during myofibril formation. By expressing N-RAP domains as GFP-fusion proteins in cultured cardiomyocytes, we found that each region of N-RAP exhibited targeting to specific areas within the cardiomyocyte, and could also disrupt myofibril assembly; these effects depended on the state of the cell, with systematic differences observed by varying the interval between culturing the cells and transfection with N-RAP constructs. We present a molecular model of myofibrillogenesis initiation that is consistent with the binding properties, targeting activities and phenotypic effects of N-RAP domains.
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Materials and Methods |
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TopSUMMARYINTRODUCTIONMaterials and MethodsRESULTSDISCUSSIONREFERENCES |
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-actinin were obtained from Sigma (St Louis, MO), and monoclonal anti-GFP was obtained from Clontech Laboratories (Palo Alto, CA).
Data analysis
Digital micrographs were captured using a Hamamatsu CCD camera connected to a Zeiss Axiovert 135 microscope and interfaced with a Power Macintosh computer, as previously described (Carroll and Horowits, 2000). Quantitative image analysis was performed on a Macintosh computer using the public domain NIH Image program (developed at the US National Institutes of Health and available at http://rsb.info.nih.gov/nih-image/).
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RESULTS |
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-actinin staining (Fig. 2B). This indicates that neither the transfection procedure nor the introduction of GFP into the cardiomyocytes hinders myofibrillogenesis and that GFP alone was not specifically targeted to any areas within the cells.
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-actinin staining. Fig. 2C shows the quantitative results for mock transfected cardiomyocytes, which were subjected to the transfection protocol with the omission of plasmid DNA (open symbols). The results for cardiomyocytes expressing GFP alone are also shown (Fig. 2C, closed symbols). Although the cells were isolated from beating embryonic hearts, 1-2 days after plating these cardiomyocytes contain few myofibrils (Fig. 2C). The myofibrillar markers -actinin and titin are clearly present at this stage, but are diffusely distributed (Carroll and Horowits, 2000), demonstrating that the pre-existing myofibrils have been completely disassembled. The cardiomyocytes formed mature myofibrils between 2 and 3 days in culture, followed by degeneration of the mature myofibrils between 4 and 5 days (Fig. 2C). The time course of myofibril assembly and disassembly was unaffected by GFP expression (Fig. 2, closed versus open symbols), and was similar to that observed in untransfected cultures (data not shown), indicating that neither the transfection procedure nor GFP expression affected these processes. Our quantitative data demonstrating myofibril disassembly within 2 days of plating, followed by myofibril assembly between 2 and 4 days, and myofibril degradation after 4 days is consistent with previous reports on the myofibrillogenesis process in cultured chick cardiomyocytes (Handel et al., 1991; Rhee et al., 1994). Therefore, between 2 and 4 days in culture there is a net assembly of myofibrils, and this period affords a suitable window in which to study the myofibrillogenesis process.
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However, some cells exhibited specific targeting of N-RAP near the membrane and along fibrillar structures (Fig. 3E, arrows), even though no significant fibrillar structures were detected with -actinin staining (Fig. 3F, arrows). However, it is not clear whether the apparent absence of -actinin in these N-RAP-positive fibrillar structures is real or whether fibrillar -actinin is obscured by the large amount of diffusely distributed -actinin that is present. Cardiomyocytes shown in the top and bottom panels of Fig. 3 were transfected at the same day in culture and viewed the same days post-plating, so the differences in myofibril formation between the transfected cells in these panels cannot be attributed to the timing of transfection. Instead, the observed differences may be due to overexpression of GFP-N-RAP in the cardiomyocyte in the lower panels relative to the transfected cell in the upper panel, as inferred from the relative amount of GFP fluorescence observed.
Expression of GFP-N-RAP-LIM
Transfection of GFP-N-RAP-LIM into cardiomyocytes after four days in culture resulted in specific targeting of this construct to areas near the membrane (Fig. 4A). In cells where GFP-N-RAP-LIM was located in these areas near the membrane, the cardiomyocyte had typically developed myofibril precursors, indicated by punctate -actinin staining (Fig. 4B), and the transfected cells were not easily distinguished from neighboring untransfected cells by -actinin staining alone. By contrast, when cardiomyocytes were transfected with GFP-N-RAP-LIM at earlier times (1-2 days), this construct exhibited a diffuse pattern of expression (Fig. 4C), and the transfected cardiomyocyte contained significantly fewer -actinin-positive myofibril structures compared with the neighboring untransfected cells, which contained large areas of well organized sarcomeres (Fig. 4D).
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-actinin staining (Fig. 5B, arrows), resembling the pattern of expression observed for GFP-N-RAP and endogenous N-RAP in similar immature areas. In areas containing well-organized sarcomeres, as indicated by the regular Z-band staining with -actinin (Fig. 5B, arrowheads), GFP-N-RAP-SR exhibited a broad-banded pattern of expression (Fig. 5A). These broad bands spanned the area on either side of the Z-line into the I-band region (Fig. 5A inset, arrowheads). However, mature sarcomeres were rarely observed when GFP-N-RAP-SR was transfected into cardiomyocytes at the earliest time in culture (1 day). The transfected cardiomyocyte in the bottom panels of Fig. 5 is typical of this observation; it was packed with myofibril precursors containing both N-RAP-SR (Fig. 5C) and -actinin (Fig. 5D), but did not contain mature myofibrils.
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-actinin staining (Fig. 6C,D).
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-actinin staining was intense but diffusely distributed (Fig. 7B). In other cases, GFP-N-RAP-IB appeared localized to structures resembling myofibril precursors and at the membrane along cell to cell borders (Fig. 7C), while no mature sarcomeres were detected by -actinin staining (Fig. 7D). In this example, the -actinin staining intensity was dramatically reduced in the transfected cell compared with the surrounding untransfected cells, which were packed with mature myofibrils (Fig. 7D).
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The effect of N-RAP domains on endogenous protein levels
As each of the N-RAP constructs expressed as GFP fusion proteins could inhibit myofibril formation, we sought to determine if endogenous -actinin and N-RAP levels were also affected. We measured the mean pixel intensity in micrographs of the -actinin staining in transfected cells and normalized these values by the mean pixel intensity in untransfected cells present on the same slide. In general, the normalized values for the -actinin levels did not significantly deviate from 1.0 for any of the constructs (Fig. 9, closed symbols). The results show that -actinin levels are normal in the transfected cells, even under conditions where myofibril assembly has been inhibited by N-RAP constructs.
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-actinin levels, we found that transfection with GFP-N-RAP-LIM led to a gradual decrease in endogenous N-RAP (Fig. 9C, open symbols). This effect occurred in cardiomyocytes transfected with GFP-N-RAP-LIM after either 1 day (open circles) or 2 days (open squares) in culture. By contrast, the effect of transfection with GFP-N-RAP-SR on endogenous N-RAP levels depended on when the cardiomyocytes were transfected; we found that when cardiomyocytes were transfected with GFP-N-RAP-SR after 2 days in culture there was no significant effect on the endogenous N-RAP staining compared with the neighboring untransfected cells (Fig. 9D, open squares). However, when cardiomyocytes were transfected with GFP-N-RAP-SR after 1 day in culture, the endogenous N-RAP levels were significantly reduced by day 4 compared with neighboring untransfected cardiomyocytes (Fig. 9D, open circles). |
DISCUSSION |
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In contrast to the N-RAP LIM domain, GFP-N-RAP-IB and GFP-N-RAP-SR were both targeted to myofibril precursors as well as to mature sarcomeres. However, their localization within the sarcomeres differed, with N-RAP-SR colocalizing with the myofilaments, and N-RAP-IB colocalizing with -actinin at the Z-lines. As the N-RAP super repeats exhibited strong actin binding in vitro but did not bind myosin (Luo et al., 1999), the broad-banded myofibrillar localization of N-RAP-SR is probably due to its incorporation into the sarcomeric actin filaments. By contrast, the targeting data for N-RAP-IB suggest an interaction between N-RAP-IB and Z-line components. N-RAP-IB was also colocalized with -actinin at the cell periphery and cell-cell contacts. N-RAP-IB directly binds muscle LIM protein (MLP) (Ehler et al., 2001), a Z-line protein (Arber et al., 1997; Flick and Konieczny, 2000) that directly binds -actinin (Flick and Konieczny, 2000; Louis et al., 1997), and this interaction may account for the complex pattern of N-RAP-IB targeting that we observe.
Disruption of myofibrillogenesis
Each of the N-RAP constructs could inhibit the formation of mature myofibrils in cultured cardiomyocytes under certain conditions (Fig. 8), showing that each region of N-RAP is crucial for myofibril assembly. As overexpression of full-length GFP-N-RAP inhibits myofibril assembly as effectively as GFP-N-RAP-LIM, the stoichiometry between N-RAP and its binding partners must be a crucial factor that affects myofibrillogenesis.
In the case of N-RAP-SR and N-RAP-IB, the effect on myofibrillogenesis was crucially dependent on the time of transfection, with complete inhibition only observed in cardiomyocytes transfected within 1 day of plating. By contrast, GFP-N-RAP and GFP-N-RAP-LIM almost completely inhibited myofibril formation whether transfection occurred within 1 or 2 days of plating. The results suggest that, once formed, the association of the N-RAP super repeats and N-RAP-IB with their binding partners is less susceptible to competitive disruption than the association between the N-RAP LIM domain and its membrane associated binding partners. Consistent with this interpretation, their homology to nebulin suggests that the repetitive actin binding modules that compose the N-RAP super repeat region should bind actin cooperatively and strongly (Chen et al., 1993; Pfuhl et al., 1996). A repetitive motif has also been identified in the N-RAP-IB region (Luo et al., 1997).
Expression of the GFP-N-RAP domains did not result in a systematic change in -actinin levels as estimated by quantitation of immunofluorescent images (Fig. 9). Our results show that -actinin was present in approximately normal amounts, but remained unassembled when myofibrillogenesis was disrupted by overexpression of N-RAP or N-RAP domains. By contrast, endogenous N-RAP levels appeared to decrease modestly in cardiomyocytes transfected with GFP-N-RAP-LIM or GFP-N-RAP-SR. The decrease in N-RAP levels appeared to be related to the inhibition of myofibril assembly, as cells expressing N-RAP-SR exhibited each of these effects only when transfected 1 day after plating.
A model for initiation of myofibrillogenesis
In cultured cardiomyocytes (Dabiri et al., 1997; Rhee et al., 1994), precardiac mesoderm explant cultures (Imanaka-Yoshida et al., 1998) and embryonic hearts (Ehler et al., 1999), the earliest myofibril precursors originate near the membrane, suggesting a role for a membrane-associated tethering molecule in the process. Although existing models of myofibrillogenesis address subsequent steps in some detail (Dabiri et al., 1997; Holtzer et al., 1997), the mechanism and role of the initial membrane association have remained unexplained. We hypothesize a crucial role for N-RAP in the first steps of myofibrillogenesis based on the following findings: (1) N-RAP binds tightly to the membrane associated proteins talin and vinculin, as well as to actin (Luo et al., 1999); (2) N-RAP is found in the earliest premyofibrils at the cell periphery (Carroll and Horowits, 2000); (3) N-RAP is expressed only in striated muscles (Luo et al., 1997); and (4) Each region of N-RAP can completely disrupt myofibril formation when expressed in cultured cardiomyocytes at particular times, consistent with a central role for N-RAP as an organizing center in the initial phase of myofibril assembly.
A schematic model illustrating one possible sequence of events leading to the initiation of myofibril assembly is shown in Fig. 10. In this scheme, N-RAP binds to a membrane-associated complex containing integrins, talin and vinculin (step 1). The N-RAP LIM domain is probably responsible for this initial interaction, as it is exclusively targeted to the cell periphery (Table 2) and binds directly to talin in vitro (Luo et al., 1999). The interaction between the N-RAP super repeats and the vinculin tail (Luo et al., 1999) may be important for appropriate positioning of the Z-line components and actin filaments that are recruited to the complex in subsequent steps.
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-actinin at Z-lines and the cell periphery (Table 2), with a direct interaction between N-RAP and the Z-line component MLP (Ehler et al., 2001), and with -actinin binding to the head region of vinculin (Kroemker et al., 1994). Nebulin repeats can nucleate actin polymerization (Chen et al., 1993; Gonsior et al., 1998), and the strong actin-binding activity of the N-RAP super repeats (Luo et al., 1999), along with their homology to nebulin (Luo et al., 1997), suggests that they would have similar effects. Our model includes actin filaments polymerizing along the N-RAP super repeats and integrating with the Z-line components bound to N-RAP-IB (step 3). By analogy with nebulin, the super repeats are expected to assign directionality to the actin filaments; this is because the orientation of nebulin in skeletal muscle sarcomeres places its C terminus at the Z-line-associated barbed end of the actin filament and its N terminus in the center of the sarcomere at the pointed end of the actin filament (Herrera et al., 2000; Wang et al., 1996; Wright et al., 1993). We hypothesize that the interactions between N-RAP super repeats and the vinculin tail (Luo et al., 1999) serve to orient the complex in a way that allows for appropriate positioning of actin filaments polymerizing along the N-RAP super repeats relative to the Z-line components bound to N-RAP-IB and vinculin.
Finally, the N-RAP containing complex of Z-bodies with associated actin filaments is released from the membrane complex (step 4), and N-RAP is removed from the complex as the Z-bodies fuse laterally to form Z-lines (step 5). As we observed N-RAP-SR and N-RAP-IB retained in mature sarcomeres, it is likely that the N-RAP LIM domain targets N-RAP for removal from the nascent myofibrils. Release from the membrane complex may be accompanied by a post-translational modification of the N-RAP LIM domain, which serves as a signal for N-RAP removal.
The model proposed in Fig. 10 provides a framework for understanding the initial recruitment and assembly of myofibrillar components, including a mechanism for controlling the polarity of the actin filaments relative to the Z-line proteins. The initial linear arrangement of newly formed Z-bodies is not addressed, but might be controlled by a periodic arrangement of the membrane proteins, for example, by integrin clustering. Future tests of this model may illuminate the precise mechanism for the initiation of myofibrillogenesis, and link our understanding of the assembly of sarcomeric components to cellular control of the assembly process by signaling mechanisms.
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REFERENCES |
|---|
|
TopSUMMARYINTRODUCTIONMaterials and MethodsRESULTSDISCUSSIONREFERENCES |
|---|
Arber, S., Hunter, J. J., Ross, J., Jr, Hongo, M., Sansig, G., Borg, J., Perriard, J. C., Chien, K. R. and Caroni, P. (1997). MLP-deficient mice exhibit a disruption of cardiac cytoarchitectural organization, dilated cardiomyopathy, and heart failure. Cell 88, 393-403.[Medline]
Burridge, K. and Chrzanowska-Wodnicka, M. (1996). Focal adhesions, contractility, and signaling. Annu. Rev. Cell Dev. Biol. 12, 463-518.[Medline]
Carroll, S. L. and Horowits, R. (2000). Myofibrillogenesis and formation of cell contacts mediate the localization of N-RAP in cultured chick cardiomyocytes. Cell Motil. Cytoskel. 47, 63-76.[Medline]
Chen, M. J., Shih, C. L. and Wang, K. (1993). Nebulin as an actin zipper. A two-module nebulin fragment promotes actin nucleation and stabilizes actin filaments. J. Biol. Chem. 268, 20327-20334.
Critchley, D. R. (2000). Focal adhesions – the cytoskeletal connection. Curr. Opin. Cell Biol. 12, 133-139.[Medline]
Dabiri, G. A., Turnacioglu, K. K., Sanger, J. M. and Sanger, J. W. (1997). Myofibrillogenesis visualized in living embryonic cardiomyocytes. Proc. Natl. Acad. Sci. USA 94, 9493-9498.
Dlugosz, A. A., Antin, P. B., Nachmias, V. T. and Holtzer, H. (1984). The relationship between stress fiber-like structures and nascent myofibrils in cultured cardiac myocytes. J. Cell Biol. 99, 2268-2278.
Ehler, E., Horowits, R., Zuppinger, C., Price, R. L., Perriard, E., Leu, M., Caroni, P., Sussman, M., Eppenberger, H. M. and Perriard, J. C. (2001). Alterations at the intercalated disk associated with the absence of muscle LIM protein. J. Cell Biol. 153, 763-772.
Ehler, E., Rothen, B. M., Hämmerle, S. P., Komiyama, M. and Perriard, J.-C. (1999). Myofibrillogenesis in the developing chicken heart: assembly of the z-disk, m-line and thick filaments. J. Cell Sci. 112, 1529-1539.[Abstract]
Flick, M. J. and Konieczny, S. F. (2000). The muscle regulatory and structural protein MLP is a cytoskeletal binding partner of betaI-spectrin. J. Cell Sci. 113, 1553-1564.[Abstract]
Gonsior, S. M., Gautel, M. and Hinssen, H. (1998). A six-module human nebulin fragment bundles actin filaments and induces actin polymerization. J. Muscle Res. Cell Motil. 19, 225-235.[Medline]
Handel, S. E., Greaser, M. L., Schultz, E., Wang, S. M., Bulinski, J. C., Lin, J. J. and Lessard, J. L. (1991). Chicken cardiac myofibrillogenesis studied with antibodies specific for titin and the muscle and nonmuscle isoforms of actin and tropomyosin. Cell Tissue Res. 263, 419-430.[Medline]
Herrera, A. H., Elzey, B., Law, D. J. and Horowits, R. (2000). Terminal regions of mouse nebulin: sequence analysis and complementary localization with N-RAP. Cell Motil. Cytoskel. 45, 211-222.[Medline]
Holtzer, H., Hijikata, T., Lin, Z. X., Zhang, Z. Q., Holtzer, S., Protasi, F., Franzini-Armstrong, C. and Sweeney, H. L. (1997). Independent assembly of 1.6 microns long bipolar MHC filaments and I-Z- I bodies. Cell Struct. Funct. 22, 83-93.[Medline]
Imanaka-Yoshida, K., Knudsen, K. A. and Linask, K. K. (1998). N-cadherin is required for the differentiation and initial myofibrillogenesis of chick cardiomyocytes. Cell Motil. Cytoskel. 39, 52-62.[Medline]
Kroemker, M., Rudiger, A. H., Jockusch, B. M. and Rudiger, M. (1994). Intramolecular interactions in vinculin control alpha-actinin binding to the vinculin head. FEBS Lett. 355, 259-262.[Medline]
Louis, H. A., Pino, J. D., Schmeichel, K. L., Pomies, P. and Beckerle, M. C. (1997). Comparison of three members of the cysteine-rich protein family reveals functional conservation and divergent patterns of gene expression. J. Biol. Chem. 272, 27484-27491.
Luo, G., Zhang, J. Q., Nguyen, T. P., Herrera, A. H., Paterson, B. and Horowits, R. (1997). Complete cDNA sequence and tissue localization of N-RAP, a novel nebulin-related protein of striated muscle. Cell Motil. Cytoskel. 38, 75-90.[Medline]
Luo, G., Herrera, A. H. and Horowits, R. (1999). Molecular interactions of N-RAP, a nebulin-related protein of striated muscle myotendon junctions and intercalated disks. Biochemistry 38, 6135-6143.[Medline]
Ojima, K., Lin, Z. X., Bang, M., Holtzer, S., Matsuda, R., Labeit, S., Sweeney, H. L. and Holtzer, H. (2000). Distinct families of Z-line targeting modules in the COOH-terminal region of nebulin. J. Cell Biol. 150, 553-566.
Pfuhl, M., Winder, S. J., Castiglione Morelli, M. A., Labeit, S. and Pastore, A. (1996). Correlation between conformational and binding properties of nebulin repeats. J. Mol. Biol. 257, 367-384.[Medline]
Rhee, D., Sanger, J. M. and Sanger, J. W. (1994). The premyofibril: evidence for its role in myofibrillogenesis. Cell Motil. Cytoskel. 28, 1-24.[Medline]
Schultheiss, T., Lin, Z. X., Lu, M. H., Murray, J., Fischman, D. A., Weber, K., Masaki, T., Imamura, M. and Holtzer, H. (1990). Differential distribution of subsets of myofibrillar proteins in cardiac nonstriated and striated myofibrils. J. Cell Biol. 110, 1159-1172.
Wang, K., Knipfer, M., Huang, Q.-Q., van Heerden, A., Hsu, L. C.-L., Gutierrez, G., Quian, X.-L. and Stedman, H. (1996). Human skeletal muscle nebulin sequence encodes a blueprint for thin filament architecture: sequence motifs and affinity profiles of tandem repeats and terminal SH3. J. Biol. Chem. 271, 4304-4314.
Wang, S. M., Greaser, M. L., Schultz, E., Bulinski, J. C., Lin, J. J. and Lessard, J. L. (1988). Studies on cardiac myofibrillogenesis with antibodies to titin, actin, tropomyosin, and myosin. J. Cell Biol. 107, 1075-1083.
Wright, J., Huang, Q. Q. and Wang, K. (1993). Nebulin is a full-length template of actin filaments in the skeletal muscle sarcomere: an immunoelectron microscopic study of its orientation and span with site-specific monoclonal antibodies. J. Muscle Res. Cell Motil. 14, 476-483.[Medline]
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