PURIFICATION AND CHARACTERIZATION OF KURLOFF CELL SIALOGLYCOPROTEINS WITH ACID-PHOSPHATASE-ACTIVITY

The major alpha 2-6 sialoglycoproteins in detergent-extracts of Kurlof f cells were purified by anion-exchange and Sambucus nigra agglutinin- affinity chromatographies. The similar ultrastructural localisations o f (1) S. nigra agglutinin-gold conjugates and (2) acid phosphatase act ivities on the Kurloff body and particularly on its myelin figures ind icated that the major alpha 2-6 sialoglycoproteins of the Kurloff cell had acid phosphatase activity. Two-dimensional electrophoresis showed that these tartrate-sensitive phosphatases corresponded to 2 acidic ( pI 3.4-3.7) polypeptides of 36 and 34 kDa. Hydrolysis with peptide-N-g lycosidases F gave a 33 kDa apoprotein rich in alanine, glutamic acid, tyrosine and lysin. A lectin-affinity study demonstrated that they co ntained hybrid type bisected and fucosylated N-linked oligosaccharides . Cytotoxic properties were previously attributed to Kurloff cells and other studies suggested that not only acid phosphatases but also alph a 2-6-linked sialic acid residues themselves may participate in natura l killer activity.