Evidence for actin involvement in cardiac Z-lines and Z-line analogues.
Canine and feline cardiac Z-lines and Z-rods were examined by electron microscopy before and after digestion of muscle fibers with Ca2+-activated protease (CAF). Removal by CAF of electron-dense material which covers Z-lines and Z-rods exposed interdigitating longitudinal filaments (6-7 nm in diameter) apparently continuous with thin filaments of the respective I-bands. The newly exposed longitudinal filaments of CAF-treated Z-lines and of CAF-treated Z-rods bound heavy meromyosin and therefore are actin. The width of Z-lines and length of Z-rods are determined by the amount of overlap of actin filaments of opposite polarity. The oblique filaments in Z-lines and Z-rods are responsible for the perpendicular periodicity of Z-lines and Z-rods, and are attributed to alpha-actinin.
D000185:Actinin / Q000378:metabolism; D000199:Actins / Q000502:physiology*; D000818:Animals; D002415:Cats; D003599:Cytoskeleton / Q000648:ultrastructure; D004285:Dogs; D005990:Glycerol; D008854:Microscopy, Electron; D009206:Myocardium / Q000648:ultrastructure*; D010447:Peptide Hydrolases / Q000378:metabolism
D000199:Actins; D000185:Actinin; D010447:Peptide Hydrolases; D005990:Glycerol