Models of muscle Z-band fine structure based on a looping filament configuration.
The fine architecture of skeletal muscle Z bands is considered in view of stereo electron microscopical evidence and current biochemical and immunological concepts, and a new Z-band model is proposed. This model is based on a looping, interlinking configuration, within the Z band, of strands which emanate from I-band (actin) filaments of adjacent sarcomeres. Two versions of the model seem presently feasible: one in which the Z-band lattice is composed of actin loops; and another in which the same pattern is derived from tropomyosin. Either version satisfies actual electron micrograph images as well as or better than prior Z-band models. Moreover, the principle of looping linkage in filament-to-filament attachment can be related to similar filament patterns seen in several adhesion sites where intracellular filaments insert on cell membranes.
D000818:Animals; D002462:Cell Membrane; D004721:Endoplasmic Reticulum; D008854:Microscopy, Electron; D008961:Models, Structural; D009124:Muscle Proteins; D009132:Muscles / Q000166:cytology*; D014562:Caudata
D009124:Muscle Proteins