High impact information on ASPH

• The results presented suggest that phospholamban, like the Ca2+-ATPase, is uniformly distributed in the network sarcoplasmic reticulum but absent from the junctional portion of the junctional sarcoplasmic reticulum [1].
• The results presented show that calsequestrin is confined to the sarcoplasmic reticulum where it is localized in the lumen of the peripheral and the interior junctional sarcoplasmic reticulum as well as in the lumen of the corbular sarcoplasmic reticulum, but absent from the lumen of the network sarcoplasmic reticulum [2].
• Digestion of cardiac and skeletal muscle junctional sarcoplasmic reticulum vesicles with calpain II. Effects on the Ca2+ release channel [3].
• High molecular weight proteins were solubilized from junctional sarcoplasmic reticulum in zwitterionic detergent and purified by size-exclusion chromatography followed by sucrose density gradient centrifugation [4].
• The cardiac high molecular weight proteins/ryanodine receptors were purified to homogeneity from junctional sarcoplasmic reticulum membranes and shown to exhibit large conductance calcium channel activity [4].

Biological context of ASPH

• cDNA cloning was used to deduce the complete amino acid sequence of canine cardiac calsequestrin, the principal Ca2+-binding protein of cardiac junctional sarcoplasmic reticulum [5].
• When cardiac junctional sarcoplasmic reticulum vesicles or partially purified ryanodine receptors are fused with planar bilayers, phosphorylation at this site activates the Ca2+ channel [6].

Anatomical context of ASPH

• Immunocytochemical labeling localized the 26-kDa protein to junctional sarcoplasmic reticulum in cardiac and skeletal muscle [7].
• Calsequestrin was localized in the lumen of peripheral junctional sarcoplasmic reticulum, as well as in the lumen of membrane-bound structures present in the central region of the I-band, while being absent from the lumen of the sarcoplasmic reticulum in the A-band region of the cardiac muscle cells [8].
• Longitudinal tubules and junctional sarcoplasmic reticulum (SR) were prepared from heart muscle microsomes by Ca2+-phosphate loading followed by sucrose density gradient centrifugation [9].
• Whereas, in canine ventricular tissue the cAMP-PDE activity in cardiomyocytes was shown on the sarcolemma, on the junctional sarcoplasmic reticulum and on subsarcolemmal cisternae [10].

Associations of ASPH with chemical compounds

• In heart failure, calsequestrin contained glycan structures that were uncharacteristic of normal junctional sarcoplasmic reticulum, consistent with altered metabolism or altered trafficking through secretory compartments [11].
• Inositol polyphosphates regulate Ca2+ efflux in a cardiac membrane subtype distinct from junctional sarcoplasmic reticulum [12].
• Following incubation of JSR with ruthenium red, Ca2+ uptake in the presence or absence of IP4 was further enhanced 2.5 fold [13].
• However, the expression of the ryanodine receptor/Ca(Ca2+)-release channel from junctional sarcoplasmic reticulum and the transverse tubular dihydropyridine-sensitive Ca2+ channel, as well as two junctional sarcoplasmic reticulum proteins of 90 kDa and 94 kDa, was greatly suppressed in transformed muscle [14].

References