Purification and Characterization of an N-Acetyllactosamine-Specific Lectin from Larvae of a Moth, Phalera flavescens

A lectin (Phalera flavescens agglutinin, PFA) of a moth (P. flavescens) has been isolated from hemolymph by DEAE-Toyopearl followed by Cellulofine GCL-1000 chromatography. On size-exclusion chromatography, PFA showed a molecular mass of about 74 kDa, and on sodium dodecyl sulfate-polyacrylamide gel electrophoresis it was separated into two different subunits, glycosylated 18-kDa and unglycosylated 17-kDa subunits, suggesting that PFA occurs as a heterotetrameric protein. N-Acetyllactosamine and laminin inhibited the hemagglutinating activity of PFA. Studies involving Synsorbs showed that PFA interacts with the Galβ1 → 4GlcNAc group and that nonsubstituted hydroxyl groups at the C-2 and C-4 positions of the galactose residue were essential for interaction with PFA, whereas substitution at the C-3 position of the galactose did not inhibit the interaction between PFA and sugar chains associated with N-acetyllactosamine. PFA is not mitogenic for native or desialylated mouse thymocytes or splenocytes.