Lectins bind to specific carbohydrate residues of glycoproteins and
glycolipids present at the cell surface. This allow them to agglutinate a
variety of cellular types. On the basis of sequence similarity and common
characteristics such as sugar binding specificity, conserved carbohydrate
recognition domains, and ion requirement the different lectins can be grouped
in different categories, like C-type, I-type, galectins, pentraxins and P-type
The sea urchin (Anthocidaris crassispina) egg lectin (SUEL) forms a new class
of lectins. Altough SUEL was first isolated as a D-galactoside binding lectin
it was latter shown that it bind to L-rhamnose preferentially [1,2]. L-rhamnose and D-galactose share the same hydroxyl group orientation at C2 and
C4 of the pyranose ring structure. SUEL is a lectin that exist as a disulfide
linked homodimer. The dimeric form is essential for hemagglutination activity
but the monomeric form retains carbohydrate binding capacity . Based on
primary structure analysis, a cysteine-rich domain homologous to the SUEL
protein has been identified in the following proteins [3,4,5]:
Plant β-galactosidases (EC 18.104.22.168) (lactases). They constitute a
widespread family of enzymes characterized by their ability to hydrolyse
terminal, non-reducing β D-galactosyl residues from β-D-galactosides.
Mammalian latrophilin, the calcium independent receptor of α-
latrotoxin (CIRL). It belongs to the secretin family of G-protein coupled
receptors. The lectin domain is not required for α-latratoxin binding
Rhamnose-binding lectin (SAL) from catfish (Parasilurus asotus) eggs. This
protein is composed of three tandem repeat domains homologous to the SUEL
lectin domain. All cysteine positions of each domain are completely
Caenorhabditis elegans hypothetical proteins B0457.1, F32A7.3A and
Human hypothetical protein KIAA0821.
December 2001 / First entry.
PROSITE method (with tools and information) covered by this documentation:
Ozeki Y., Matsui T., Suzuki M., Titani K.
Amino acid sequence and molecular characterization of a D-galactoside-specific lectin purified from sea urchin (Anthocidaris crassispina) eggs.
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