YAMADA, K, SASAKI, T. and SAKAGAMI. T, Measurement of Isoelectric Points of Phospholipid Exchange Proteins by Gel Isoelectric Focusing. Tohoku J. exp. Med., 1981, 135 (1), 37-42 - A method of the estimation of isoelectric points of phospholipid exchange proteins is described. The phospholipid presumably bound to a phospholipid exchange protein was replaced with [³H]phosphatidylcholine of a high specific radioactivity by an incubation of the protein with liposomes containing the labeled lipid and dimannosyl diglyceride. After the incubation, a major portion of the liposomes was separated from the protein by an affinity of the liposomes to concanavalin A-Sepharose 2B. The isoelectric point of the protein was measured by gel isoelectric focusing of the protein, which was located by tritium radioactivity of the bound [³H]phosphatidylcholine. The method was used to measure isoelectric points of partially purified phospholipid exchange proteins in pig liver.