title: ATP-dependent calcium transport by a Golgi-enriched membrane fraction from mouse mammary gland.
abstract: Crude particulate preparations from the mammary glands of lactating mice were shown to transport calcium against a concentration gradient in the presence of ATP and mitochondrial inhibitors. Density gradient centrifugation with both sucrose and Percoll gradients indicated the presence of ATP-dependent transport in more than one membrane fraction. A Golgi-enriched membrane fraction possessed the highest specific activity of calcium transport. Digitonin, which increases the permeability of plasma membranes to calcium, did not affect this process. The Golgi fraction contained a 100,000 Dalton protein whose phosphorylation by gamma-[32P]-ATP was enhanced by a micromolar concentrations of free calcium. The phosphorylation was acid-stable and hydroxylamine-sensitive. These properties suggest that Golgi membranes in an activity secreting mammary epithelium possess a calcium transport system which resembles the calcium ATPase present in the sarcoplasmic reticulum of skeletal muscle.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D005260:Female; D006056:Golgi Apparatus / Q000378:metabolism*; D007425:Intracellular Membranes / Q000378:metabolism; D007774:Lactation; D008321:Mammary Glands, Animal / Q000378:metabolism*; D051379:Mice; D008970:Molecular Weight; D009245:NADH Dehydrogenase / Q000378:metabolism; D010766:Phosphorylation; D011247:Pregnancy; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
chemical_list: D000001:Calcimycin; D000255:Adenosine Triphosphate; D009245:NADH Dehydrogenase; D000252:Calcium-Transporting ATPases; D000254:Sodium-Potassium-Exchanging ATPase; D002118:Calcium