Direct attachment of membrane to the Z-band of rabbit skeletal myofibrils.

In preparations of isolated myofibrils from rabbit white skeletal muscle, strands could be seen attached to the myofibrils at the level of the Z-band. The membranous nature of these strands was suggested by their appearance and was confirmed by their removal with the detergent, Triton X-100. The membrane appeared to be connected directly with the Z-band, with no intervening filaments or cables. It is suggested that these direct connections serve to anchor the sarcoplasmic reticulum to the myofibrils.