Isolation and characterization of an N-acetyllactosamine-binding lectin from the mushroom Laetiporus sulfureus

A hemagglutinating and hemolytic lectin (PSL) has been isolated from carpophores of the parasitic mushroom Laetiporus sulfureus by affinity chromatography on Sepharose. Its molecular weight, as determined both by gel filtration and by electrophoresis in non-denaturing conditions, is about 190,000 and its structure is tetrameric, with two distinct types of subunits (about 60,000 and 36,000). It appeared homogeneous on HPLC gel filtration but exhibited microheterogeneity on isoelectric focusing. Hapten inhibition assay indicated that the Laetiporus lectin is specific for N-acetyllactosamine residues and that hemagglutinating and hemolysis activities are supported by the same site.