This technical figure was developed for the Karolinska Institute in Sweden. It depicts a sarcomere, the basic contractile unit of a muscle fibre. The displayed sarcoplasmic reticulum is the primary regulator of calcium storage, release, and reuptake while the mitochondria are responsible for cellular ATP production.
The sarcomere is the functional unit responsible for allowing the contraction of muscles. It consists of a bundle of myosin-containing thick filaments (depicted in purple) flanked and interdigitated with bundles of actin-containing thin filaments (depicted in green/red). The Z disk marks the lateral boundaries of the sarcomere and serves as the anchoring point of the actin filaments. The genes "Mybpc3" and "Ttn" are essential for the production of proteins that enable correct interaction of actin and myosin during contraction. The sarcoplasmic reticulum provides the calcium that is required for muscle contractions.