Sarcoplasmic reticulum: structural determinants and protein dynamics.

The sarcoplasmic reticulum is a unique organelle found in muscle cells that is dedicated to the regulation of Ca(2+) homeostasis and activation of myofilament contraction. The functional requirement for an efficient and synchronous activation of Ca(2+) release from the SR, following the depolarization of the plasma membrane, accounts for the complex three-dimensional organization of internal membranes observed in muscle cells and for the localization of proteins at specific sites of the SR. Recent advancements in understanding the molecular basis of SR structure and function have greatly increased our understanding of muscle cellular physiology and biology. Parallel work has revealed that several human diseases affecting skeletal and cardiac tissues are linked to either mutations or altered post-translational modifications of SR proteins.