Calcium binding to rat heart plasma membranes: isolation and purification of a lipoprotein component with a high calcium binding capacity

Abstract

A Ca binding lipoprotein component of rat heart plasma membrane was isolated, purified and characterized. The lipoprotein complex had an apparent MW of 71,400. One mole of lipoprotein contained 90 mol of phospholipid and 1 mol of a 12,300 MW protein. The maximum Ca binding capacity was 4.27 .mu.mol/mg of protein, which corresponded to 52 mol of Ca per mol of lipoprotein complex. Ca binding was competitively inhibited by a variety of metal ions and experimental antiarrhythmic and anesthetic agents.