Active calcium transport via coupling between the enzymatic and the ionophoric sites of Ca/sup 2 +/ + Mg/sup 2 +/-ATPase

Journal Article · Sat Jan 01 04:00:00 EST 1977 · J. Supramol. Struct.; (United States)

DOI:https://doi.org/10.1002/jss.400060307· OSTI ID:6623907

Shamoo, A E; Scott, T L; Ryan, T E

The 20K dalton fragment of Ca/sup 2 +/ + Mg/sup 2 +/-ATPase obtained from the tryptically digested sarcoplasmic reticulum has been further purified using Bio-Gel P-100. This removed low-molecular-weight UV-absorbing and positive Lowry-reacting contaminants. The ionophoric activity of the 20K fragment in both oxidized cholesterol and phosphatidylcholine:cholesterol membranes is unaltered by this further purification. The 20K selectivity sequence in phosphatidylcholine:cholesterol membranes is Ba/sup 2 +/ > Ca/sup 2 +/ > Sr/sup 2 +/ > Mn/sup 2 +/ > Mg/sup 2 +/. Digestion of intact sarcoplasmic reticulum vesicles with trypsin, which results in the dissection of the hydrolytic site (30K) from the ionophoric site (20K), is shown to disrupt energy transduction between ATP hydrolysis and calcium transport. This further implicates the 20K dalton fragment as a calcium transport site. These data and previous evidence are discussed in terms of a proposed model for the ATPase molecular structure and the mechanism of cation transport in sarcoplasmic reticulum.

• Research Organization: Univ. of Rochester, NY
• OSTI ID: 6623907
• Journal Information: J. Supramol. Struct.; (United States), Journal Name: J. Supramol. Struct.; (United States) Vol. 6; ISSN JSPMA
• Country of Publication: United States
• Language: English

Related Subjects

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59 BASIC BIOLOGICAL SCIENCES
ALKALINE EARTH METALS
ATP-ASE
BARIUM
BIOCHEMISTRY
CALCIUM
CATIONS
CELL CONSTITUENTS
CHARGED PARTICLES
CHEMICAL REACTIONS
CHEMISTRY
CHOLESTEROL
DECOMPOSITION
ELECTROPHORESIS
ELEMENTS
ENERGY TRANSPORT
ENZYMES
ESTERASES
HYDROLASES
HYDROLYSIS
HYDROXY COMPOUNDS
ION EXCHANGE MATERIALS
IONS
LYSIS
MAGNESIUM
MANGANESE
MEMBRANES
METALS
ORGANIC COMPOUNDS
PHOSPHATASES
PROTEINS
SOLVOLYSIS
STEROIDS
STEROLS
STRONTIUM
STRUCTURAL MODELS
TRANSITION ELEMENTS