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 [(PUBMED:9132060), (PUBMED:7664110)]:
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.
Family alignment:
There are 1587
B_lectin domains in 1483 proteins in SMART's nrdb database.
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Evolution (species in which this domain is found)
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This tree shows only several representative species. The complete taxonomic breakdown of all proteins with B_lectin domain is also avaliable.
Mannose-specific agglutinin (lectin) from snowdrop (galanthus nivalis) bulbs in complex with mannose-alpha1,6- (mannose-alpha1,3)-mannose-alpha1,6-(mannose-alpha1,3)- mannose
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