The Synthesis and Insertion of Lumenal Sarcoplasmic Reticulum Proteins during Development of Skeletal Muscle

The sarco/endoplasmic reticulum of skeletal muscle is a major intracellular compartment representing 2-9% of the cell volume in fast-twitch fibers and 1-3% of the cell volume in slow-twitch fibers of various animals (for review, see Martonosi et al., 1987). It consists of two morphologically and functionally distinct but continuous subcompartments, the junctional sarcoplasmic reticulum and the free sarcoplasmic reticulum (Fig. 4.1, 4.2).