Biomaterial Database

Rapid kinetic characterization of active transport and passive release of calcium in vesicular fragments of longitudinal and junctional sarcoplasmic reticulum. 1988

G Inesi

Department of Biological Chemistry, University of Maryland School of Medicine, Baltimore 21201.

1. Vesicular fragments of longitudinal and cisternal-junctional sarcoplasmic reticulum can be obtained, selectively, from skeletal muscle. 2. Longitudinal sarcoplasmic reticulum vesicles have a high content of Ca2+-ATPase, and provide the best system for characterization of the calcium pump. Equilibrium and transient state measurements provide equilibrium and kinetic constants for the partial reactions of the catalytic and transport cycle, including binding and translocation steps. Free energy estimates are then obtained based on an explicit mechanism, rather than simply on a transmembrane gradient (which is independent of the reaction mechanism). Kinetic evidence for a sequential pattern of calcium binding and translocation is presented. 3. The cisternal-junctional membrane contains (in addition to Ca2+-ATPase) calsequestrin and a large protein (MW greater than or equal to 350,000 Da) which corresponds to the junctional processes ("feet") and binds ryanodine. This protein is involved in rapid release of Ca2+ from loaded vesicles.

UI	MeSH Term	Description	Entries
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D005374	Filtration	A process of separating particulate matter from a fluid, such as air or a liquid, by passing the fluid carrier through a medium that will not pass the particulates. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Filtrations
D000252	Calcium-Transporting ATPases	Cation-transporting proteins that utilize the energy of ATP hydrolysis for the transport of CALCIUM. They differ from CALCIUM CHANNELS which allow calcium to pass through a membrane without the use of energy.	ATPase, Calcium,Adenosinetriphosphatase, Calcium,Ca(2+)-Transporting ATPase,Calcium ATPase,Calcium Adenosinetriphosphatase,Adenosine Triphosphatase, Calcium,Ca2+ ATPase,Calcium-ATPase,ATPase, Ca2+,ATPases, Calcium-Transporting,Calcium Adenosine Triphosphatase,Calcium Transporting ATPases,Triphosphatase, Calcium Adenosine
D001693	Biological Transport, Active	The movement of materials across cell membranes and epithelial layers against an electrochemical gradient, requiring the expenditure of metabolic energy.	Active Transport,Uphill Transport,Active Biological Transport,Biologic Transport, Active,Transport, Active Biological,Active Biologic Transport,Transport, Active,Transport, Active Biologic,Transport, Uphill
D012519	Sarcoplasmic Reticulum	A network of tubules and sacs in the cytoplasm of SKELETAL MUSCLE FIBERS that assist with muscle contraction and relaxation by releasing and storing calcium ions.	Reticulum, Sarcoplasmic,Reticulums, Sarcoplasmic,Sarcoplasmic Reticulums