3D Structure of the Z-band

Z7742-a-ls-for-Z-line.jpg (35851 bytes)

The Z-band (Z-line, Z-disc) is an intriguing structure that tethers actin filaments from adjacent sarcomeres into a tetragonal lattice.  During contraction, the tension generated between the myosin and actin filaments is transmitted through the Z-band components to the adjoing sarcomere and so to the ends of the fibre.

To understand the 3D structure of the Z-band, we need to obtain different views by tilting the section about the filament axis (vertical here).  The different views are combined by computer and a 3D reconstruction done by Fourier methods or by tomography.  The following analysis is from my paper on 3D structure of the Z-band in fish fin muscle: Luther (2000).

Z-band tilts raw.jpg (45890 bytes)

These are different lattice views of the Z-band in fish fin muscle. 

zbw98_fig.fs1.jpg (8014 bytes)

Average lattice views from previous figure.  We refer to these views as (a) [10], (b) [01], (c) [11] & (d) [1-1].  The Fourier transforms were combined and then 3D reconstruction was calculated.

Z-band_plaice_3D_10_view.jpg (28875 bytes)

3D reconstruction of Z-band in fish fin muscle; left, stereo view; right, superimposed on average lattice view.

Z-band_plaice_DC3_model_TS.JPG (21918 bytes)

Stereo view of 3D model of fish fin muscle Z-band, TS view.

Z-band_plaice_DC3_model_10_view.JPG (27457 bytes)

Stereo view of 3D model of fish fin muscle Z-band, [10] view.  This Z-band comprises 3 layers of α-actinin (labelled Z0, Z1 and Z1'). 

Movie showing the path of the 3 layers of α-actinin links (black) between actin filaments from adjacent sarcomeres