Ligand-gated channel of the sarcoplasmic reticulum Ca2+ transport ATPase |
| |
Authors: | Herman Wolosker Leopolde de Meis |
| |
Institution: | (1) Institute de Ciencias Biomédicas, Departamento de Bioqu mica Médica, Universidade Federal do Rio de Janeiro, Cidade Universitaria, 21941-590 Rio de Janerio, Brazil |
| |
Abstract: | In resting muscle, cytoplasmic Ca2+ concentration is maintained at a low level by active Ca2+ transport mediated by the Ca2+ ATPase from sarcoplasmic reticulum. The region of the protein that contains the catalytic site faces the cytoplasmic side of the membrane, while the transmembrane helices form a channel-like structure that allows Ca2+ translocation across the membrane. When the coupling between the catalytic and transport domains is lost, the ATPase mediates Ca2+ efflux as a Ca2+ channel. The Ca2+ efflux through the ATPase channel is activated by different hydrophobic drugs and is arrested by ligands and substrates of the ATPase at physiological pH. At acid pH, the inhibitory effect of cations is no longer observed. It is concluded that the Ca2+ efflux through the ATPase may be sufficiently fast to support physiological Ca2+ oscillations in skeletal muscle, that occur mainly in conditions of intracellular acidosis. |
| |
Keywords: | Ca2+-ATPase sarcoplasmic reticulum Ca2+ efflux |
本文献已被 SpringerLink 等数据库收录! |
|