Аннотация
The sarcoplasmic reticulum (SR) of striated muscle fibers interacts
with exterior membranes (surface membrane and transverse tubules)
to form junctions that are involved in the internal release of calcium
during excitation-contraction coupling. Release of calcium through
the ryanodine receptors (RyRs) or calcium release channels of the
SR is under the control of the L type calcium channels or dihydropyridine
receptors (DHPRs) of exterior membranes. Interacting clusters of
the two proteins constitute calcium release units. The cytoplasmic
domains of RyRs are visible as large electron-dense structures (the
feet) with four identical subunits in the junctional gap separating
SR from exterior membranes. In freeze-fracture replicas of skeletal
muscle, large intramembrane particles are grouped into clusters of
tetrads in the exterior membranes, and the tetrads are located in
correspondence of the four subunits of the feet. Lack of tetrads
in dysgenic muscle fibers with a null mutation for DHPRs and appearance
of the tetrads after transfection with cDNA for DHPR indicate identity
of tetrads with four DHPRs. In cardiac muscle, DHPRs are located
at the sites of SR-surface junctions, but they are not grouped into
tetrads. This is consistent with a possible direct DHPR-RyR interaction
in skeletal but not in cardiac muscle. The size and distribution
of SR-surface junctions in skeletal and cardiac muscles provide further
clues to their function.
- 10603933
- animals,
- calcium
- calcium,
- channel,
- channels,
- heart,
- l-type,
- muscle,
- myocardium,
- receptor
- release
- reticulum,
- ryanodine
- sarcoplasmic
- skeletal,
Пользователи данного ресурса
Пожалуйста,
войдите в систему, чтобы принять участие в дискуссии (добавить собственные рецензию, или комментарий)