title: The ability of the mitochondrial Ca2+-binding glycoprotein to restore Ca2+ transport in glycoprotein-depleted rat liver mitochondria.
abstract: Rat liver mitochondria may be subfractionated in sediment and supernatant fractions by swelling in the presence of EDTA and oxaloacetate. The sediment is largely depleted of the Ca2+-binding glycoprotein and its Ca2+-transporting activity may be as low as 10--20% of the starting value. Both the rate of Ca2+ uptake and the capacity to maintain a high Ca2+ concentration gradient across the membrane are depressed. Addition of an osmotic supernatant to the assay mixture may partially restore the original Ca2+-transporting ability. The active component in the supernatant is the Ca2+-binding glycoprotein. This is shown by the following facts: (a) the effect is enhanced by the addition of the purified glycoprotein to the supernatant; (b) precipitation of the glycoprotein from the supernatant by affinity chromatography-purified antibodies abolishes the stimulatory effect, and (c) in the presence of 130 microM Mg2+, the glycoprotein alone may restore fully the Ca2+-transporting ability of the particles. The maximal velocity is already reached at 0.1 microgram glycoprotein/mg mitochondrial protein.
mesh_terms: D000818:Animals; D001150:Arsenazo III; D002118:Calcium / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000276:immunology / Q000378:metabolism*; D004492:Edetic Acid; D006023:Glycoproteins / Q000378:metabolism*; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism*; D010071:Oxaloacetates / Q000494:pharmacology; D051381:Rats
chemical_list: D002135:Calcium-Binding Proteins; D006023:Glycoproteins; D010071:Oxaloacetates; D001150:Arsenazo III; D004492:Edetic Acid; D002118:Calcium