Horseshoe crab (Limulus polyphemus) lectin but not garden snail (Helix pomatia) lectin elicits insulin-like activities in vitro

Lectins from the horseshoe crab (Limulus polyphemus) and the garden snail (Helix pomatia) were tested for insulinomimetic activities in isolated rat epididymal adipocytes. The sialic acid binding horseshoe crab lectin suppressed epinephrine-induced lipolysis and augmented lipogenesis from D-3-3H]-glucose while the N-acetylgalactosamine binding snail lectin was inactive. The results suggest that the insulin receptor on rat adipocytes contains sialic acid in its carbohydrate moiety but does not possess non-reducing alpha-D-galactopyranosyl or 2-acetamido-2-deoxy-alpha-D-galactopyranosyl end groups.