Title: T-tubule - Wikipedia
Headings: T-tubule
T-tubule
Contents
Structure
Regulators
Function
Excitation-contraction coupling
Calcium control
Detubulation
History
Clinical significance
See also
References

Content: Regulators
The shape of the T-tubule system is produced and maintained by a variety of proteins. The protein amphiphysin-2 is encoded by the gene BIN1 and is responsible for forming the structure of the T-tubule and ensuring that the appropriate proteins (in particular L-type calcium channels) are located within the T-tubule membrane. Junctophilin-2 is encoded by the gene JPH2 and helps to form a junction between the T-tubule membrane and the sarcoplasmic reticulum, vital for excitation-contraction coupling. Titin capping protein or Telethonin is encoded by the gene TCAP and helps with T-tubule development and is potentially responsible for the increasing number of T-tubules seen as muscles grow. Function
Excitation-contraction coupling
See also: Excitation-contraction coupling
T-tubules are an important link in the chain from electrical excitation of a cell to its subsequent contraction (excitation-contraction coupling). When contraction of a muscle is needed, stimulation from a nerve or an adjacent muscle cell causes a characteristic flow of charged particles across the cell membrane known as an action potential. At rest, there are fewer positively charged particles on the inner side of the membrane compared to the outer side, and the membrane is described as being polarised. During an action potential, positively charged particles (predominantly sodium and calcium ions) flow across the membrane from the outside to the inside. This reverses the normal imbalance of charged particles and is referred to as depolarisation.