Cell wall proteins from sugar beet cells in suspension culture

Several proteins were extracted from the purified cell walls of suspension-cultured sugar beet cells with 0.5% EDTA (pH 6.8) after prior extraction of the walls with 0.5% deoxycholate and then with 2 molar NaCl. Two abundant proteins (P-I and P-II protein) were separately purified to homogeneity by procedures that included fractionation with ammonium sulfate, column chromatography on DEAE-cellulose and butyl Toyopearl, and preparative polyacrylamide electrophoresis. P-I exists as a dimer of identical subunits, and P-II is composed of four different subunits. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that quite different polypeptides are present in the culture medium and in the NaCl and EDTA extracts of the wall.