A bulb lectin super-family (Amaryllidaceae, Orchidaceae and Aliaceae) contains a ~115-residue-long domain whose overall three dimensional fold is very similar to that of [1, 2]:

• Dictyostelium discoideum comitin, an actin binding protein
• Curculigo latifolia curculin, a sweet tasting and taste-modifying protein

This domain generally binds mannose, but in at least one protein, curculin, it is apparently devoid of mannose-binding activity.

Each bulb-type lectin domain consists of three sequential beta-sheet subdomains (I, II, III) that are inter-related by pseudo three-fold symmetry. The three subdomains are flat four-stranded, antiparrallel beta-sheets. Together they form a 12-stranded beta-barrel in which the barrel axis coincides with the pseudo 3-fold axis.

1. Curculin, a sweet-tasting and taste-modifying protein, is a non-functional mannose-binding lectin. Plant Mol. Biol. 33, 691-8
2. Structure of mannose-specific snowdrop (Galanthus nivalis) lectin is representative of a new plant lectin family. Nat. Struct. Biol. 2, 472-9

A bulb lectin super-family (Amaryllidaceae, Orchidaceae and Aliaceae) contains a ~115-residue-lon
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