Preparative isolation of glycoproteins from plasma membranes of different rat organs

By a combination of high-performance affinity chromatographic (HPAC) methods, several membrane proteins from liver, Morris hepatoma and kidney were isolated. The use of a tandem system, consisting of a concanavalin A (ConA) and a wheat germ agglutinin (WGA) high-performance liquid chromatographic (HPLC) column, as a first purification step allowed the isolation of proteins directly from organ homogenates. In a subsequent step, the membrane proteins can be isolated by simply using a combination of immunoaffinity HPLC and preparative sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). However, with these methods most proteins lose their biological activity. If native proteins are required, a combination of different HPAC methods has to be applied. Several membrane proteins were isolated in milligram amounts under non-denaturing conditions using either HPAC columns or Mem Sep membranes with immobilized lectins, collagen, amino acids, crown ethers or heparin.