Group:MUZIC: Difference between revisions

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One of the functionally most complex sub-compartments of the sarcomere is the Z-disc that forms the lateral boundaries between adjacent sarcomeres. This region plays a central role as the site organizing thick filaments and titin into the molecular machinery that is required for muscle contraction and comprises the actin, titin, and nebulin filaments.

[[Image:Z-discmodelfigure last.jpg|left|800px]]

'''Figure 2''' ''Z-disk ultrastructure. (A) Antiparallel arrangement of actin filaments (grey) interconnected by several layers of α-actinin (green and red) forming an overlapping zigzag like structure (B) The same view rotated by 90deg. Figure was prepared by Dr Stephan Lange (UCSD) ''

Thin filaments (actin) from adjacent sarcomeres are anchored at the Z-disc. In this area of the sarcomere, each actin filament overlaps with four filaments from the opposite sarcomere, forming a square lattice, which is cross-connected in a zig-zag pattern by α-actinin-2 <ref>PMID:19830582</ref> ('''Figure 2'''). This region plays a central role as the main anchoring point of the molecular machinery for muscle contraction comprising the actin, titin, and nebulin filaments <ref>PMID:22028589</ref><ref>PMID:9476658</ref>.

Z-discs are also implicated in mechanosensing and signaling to the nucleus, which contribute to maintenance of muscle homeostasis, and serve as attachment sites for desmin intermediate filaments and often for transverse tubules [reviewed in <ref>PMID:12556452</ref><ref>PMID:21190822</ref><ref>PMID:21347754</ref>]. The assembly of the Z-disc is controlled via N-terminal part of titin, which exhibits binding sites for α-actinin-2 as well as to additional Z-disc components. The most striking feature of muscle and Z-disc proteins, in particular, is the diversity of multiple protein-protein interactions that form part of a complex network, involving more than forty proteins<ref name="r2">PMID:12142273</ref><ref>PMID:16416311</ref><ref>PMID:15810059</ref> ('''Figure 3'''). For example, titin binds to α-actinin-2 via 45-residue sequence motifs, the so-called Z-repeats <ref>PMID:9003807</ref> and dimerizes at its N-terminal through the mediator protein telethonin <ref>PMID:16407954</ref>.

Z-discs are also implicated in mechanosensing and signaling to the nucleus, which contribute to maintenance of muscle homeostasis, and serve as attachment sites for desmin intermediate filaments and often for transverse tubules [reviewed in <ref>PMID:12556452</ref><ref>PMID:21190822</ref><ref>PMID:21347754</ref>]. The assembly of the Z-disc is controlled via N-terminal part of titin, which exhibits binding sites for α-actinin-2 as well as to additional Z-disc components. The most striking feature of muscle and Z-disc proteins, in particular, is the diversity of multiple protein-protein interactions that form part of a complex network, involving more than forty proteins<ref name="r1">PMID:12142273</ref><ref>PMID:16416311</ref><ref>PMID:15810059</ref> ('''Figure 3'''). For example, titin binds to α-actinin-2 via 45-residue sequence motifs, the so-called Z-repeats <ref>PMID:9003807</ref> and dimerizes at its N-terminal through the mediator protein telethonin <ref>PMID:16407954</ref>.

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 One of the functionally most complex sub-compartments of the sarcomere is the Z-disc that forms the lateral boundaries between adjacent sarcomeres. This region plays a central role as the site organizing thick filaments and titin into the molecular machinery that is required for muscle contraction and comprises the actin, titin, and nebulin filaments.
+[[Image:Z-discmodelfigure last.jpg|left|800px]]
+'''Figure 2''' ''Z-disk ultrastructure. (A) Antiparallel arrangement of actin filaments (grey) interconnected by several layers of α-actinin (green and red) forming an overlapping zigzag like structure (B) The same view rotated by 90deg. Figure was prepared by Dr Stephan Lange (UCSD) ''
 Thin filaments (actin) from adjacent sarcomeres are anchored at the Z-disc. In this area of the sarcomere, each actin filament overlaps with four filaments from the opposite sarcomere, forming a square lattice, which is cross-connected in a zig-zag pattern by α-actinin-2 <ref>PMID:19830582</ref> ('''Figure 2'''). This region plays a central role as the main anchoring point of the molecular machinery for muscle contraction comprising the actin, titin, and nebulin filaments <ref>PMID:22028589</ref><ref>PMID:9476658</ref>.
-Z-discs are also implicated in mechanosensing and signaling to the nucleus, which contribute to maintenance of muscle homeostasis, and serve as attachment sites for desmin intermediate filaments and often for transverse tubules [reviewed in <ref>PMID:12556452</ref><ref>PMID:21190822</ref><ref>PMID:21347754</ref>]. The assembly of the Z-disc is controlled via N-terminal part of titin, which exhibits binding sites for α-actinin-2 as well as to additional Z-disc components. The most striking feature of muscle and Z-disc proteins, in particular, is the diversity of multiple protein-protein interactions that form part of a complex network, involving more than forty proteins<ref name="r2">PMID:12142273</ref><ref>PMID:16416311</ref><ref>PMID:15810059</ref> ('''Figure 3'''). For example, titin binds to α-actinin-2 via 45-residue sequence motifs, the so-called Z-repeats <ref>PMID:9003807</ref> and dimerizes at its N-terminal through the mediator protein telethonin <ref>PMID:16407954</ref>.
+Z-discs are also implicated in mechanosensing and signaling to the nucleus, which contribute to maintenance of muscle homeostasis, and serve as attachment sites for desmin intermediate filaments and often for transverse tubules [reviewed in <ref>PMID:12556452</ref><ref>PMID:21190822</ref><ref>PMID:21347754</ref>]. The assembly of the Z-disc is controlled via N-terminal part of titin, which exhibits binding sites for α-actinin-2 as well as to additional Z-disc components. The most striking feature of muscle and Z-disc proteins, in particular, is the diversity of multiple protein-protein interactions that form part of a complex network, involving more than forty proteins<ref name="r1">PMID:12142273</ref><ref>PMID:16416311</ref><ref>PMID:15810059</ref> ('''Figure 3'''). For example, titin binds to α-actinin-2 via 45-residue sequence motifs, the so-called Z-repeats <ref>PMID:9003807</ref> and dimerizes at its N-terminal through the mediator protein telethonin <ref>PMID:16407954</ref>.