A SIALIC ACID-BINDING LECTIN FROM OVINE PLACENTA - PURIFICATION, SPECIFICITY AND INTERACTION WITH ACTIN

A sialic-acid-specific lectin from ovine placental cotyledons was puri fied by affinity chromatography on bovine submaxillary mucin-agarose f ollowed by gel filtration, and it showed a molecular weight of 65 000 by sodium dodecylsulfate-polyacrylamide gel electrophoresis. This lect in has the capacity to interact with actin, since it binds to actin-F in a cosedimentation assay and it acts as a mediator in the binding of actin to the affinity column. The lectin agglutinated rabbit and rat erythrocytes, but not human A, B or O erythrocytes. Haemagglutination inhibition assays of different saccharides, glycoproteins and glycolip ids indicate that this lectin has affinity for sialic acid, which is e nhanced by its O-acetylation. The N-terminal sequence of the protein s hows 92% identity with rabbit and porcine uterine calreticulin.