PROSITE documentation PDOC00279

Galactoside-binding lectin (galectin) domain profile


Galectins (also known as galaptins or S-lectin) are a family of proteins defined by having at least one characteristic carbohydrate recognition domain (CRD) with an affinity for β-galactosides and sharing certain sequence elements. Members of the galectins family are found in mammals, birds, amphibians, fish, nematodes, sponges, and some fungi. Galectins are known to carry out intra- and extracellular functions through glycoconjugate-mediated recogntion. From the cytosol they may be secreted by non-classical pathways, but they may also be targeted to the nucleus or specific sub-cytosolic sites. Within the same peptide chain some galectins have a CRD with only a few additional amino acids, whereas others have two CRDs joined by a link peptide, and one (galectin-3) has one CRD joined to a different type of domain [1,2,3].

The galectin carbohydrate recognition domain (CRD) is a β-sandwich of about 135 amino acid (see <PDB:1HLC>). The two sheets are slightly bent with 6 strands forming the concave side and 5 strands forming the convex side. The concave side forms a groove in which carbohydrate is bound, and which is long enough to hold about a linear tetrasaccharide [1,2,3,4,5].

A number of proteins are known to belong to this family:

  • Galectin-3 (also known as MAC-2 antigen; CBP-35 or IgE-binding protein), a 35 Kd lectin which binds immunoglobulin E and which is composed of two domains: a N-terminal domain that consist of tandem repeats of a glycine/ proline-rich sequence and a C-terminal galectin domain.
  • Galectin-4 [6], which is composed of two galectin domains.
  • Galectin-5.
  • Galectin-7 [7], a keratinocyte protein which could be involved in cell-cell and/or cell-matrix interactions necessary for normal growth control.
  • Galectin-8 [8], which is composed of two galectin domains.
  • Galectin-9 [9], which is composed of two galectin domains.
  • Human eosinophil lysophospholipase (EC [5] (Charcot-Leyden crystal protein), a protein that may have both an enzymatic and a lectin activities. It forms hexagonal bipyramidal crystals in tissues and secretions from sites of eosinophil-associated inflammation.
  • Caenorhabditis elegans 32 Kd lactose-binding lectin [10]. This lectin is composed of two galectin domains.
  • Caenorhabditis elegans lec-7 and lec-8.

The profile we developed covers the entire galectin domain.

Last update:

March 2007 / Pattern removed, profile added and text revised.

Technical section

PROSITE method (with tools and information) covered by this documentation:

GALECTIN, PS51304; Galactoside-binding lectin (galectin) domain profile  (MATRIX)


1AuthorsLeffler H.
TitleIntroduction to galectins.;
SourceTrends Glycosci. Glycotechnol. 9:9-19(1997).

2AuthorsLeffler H., Carlsson S., Hedlund M., Qian Y., Poirier F.
TitleIntroduction to galectins.
SourceGlycoconj. J. 19:433-440(2004).
PubMed ID14758066

3AuthorsBan M., Yoon H.-J., Demirkan E., Utsumi S., Mikami B., Yagi F.
TitleStructural basis of a fungal galectin from Agrocybe cylindracea for recognizing sialoconjugate.
SourceJ. Mol. Biol. 351:695-706(2005).
PubMed ID16051274

4AuthorsLobsanov Y.D., Gitt M.A., Leffler H., Barondes S.H., Rini J.M.
TitleX-ray crystal structure of the human dimeric S-Lac lectin, L-14-II, in complex with lactose at 2.9-A resolution.
SourceJ. Biol. Chem. 268:27034-27038(1993).
PubMed ID8262940

5AuthorsLeonidas D.D., Elbert B.L., Zhou Z., Leffler H., Ackerman S.J., Acharya K.R.
TitleCrystal structure of human Charcot-Leyden crystal protein, an eosinophil lysophospholipase, identifies it as a new member of the carbohydrate-binding family of galectins.
SourceStructure 3:1379-1393(1995).
PubMed ID8747464

6AuthorsOda Y., Herrmann J., Gitt M.A., Turck C.W., Burlingame A.L., Barondes S.H., Leffler H.
TitleSoluble lactose-binding lectin from rat intestine with two different carbohydrate-binding domains in the same peptide chain.
SourceJ. Biol. Chem. 268:5929-5939(1993).
PubMed ID8449956

7AuthorsMadsen P., Rasmussen H.H., Flint T., Gromov P., Kruse T.A., Honore B., Vorum H., Celis J.E.
TitleCloning, expression, and chromosome mapping of human galectin-7.
SourceJ. Biol. Chem. 270:5823-5829(1995).
PubMed ID7534301

8AuthorsHadari Y.R., Paz K., Dekel R., Mestrovic T., Accili D., Zick Y.
TitleGalectin-8. A new rat lectin, related to galectin-4.
SourceJ. Biol. Chem. 270:3447-3453(1995).
PubMed ID7852431

9AuthorsWada J., Kanwar Y.S.
TitleIdentification and characterization of galectin-9, a novel beta-galactoside-binding mammalian lectin.
SourceJ. Biol. Chem. 272:6078-6086(1997).
PubMed ID9038233

10AuthorsHirabayashi J., Satoh M., Kasai K.-I.
TitleEvidence that Caenorhabditis elegans 32-kDa beta-galactoside-binding protein is homologous to vertebrate beta-galactoside-binding lectins. cDNA cloning and deduced amino acid sequence.
SourceJ. Biol. Chem. 267:15485-15490(1992).
PubMed ID1639789

11AuthorsAbbott W.M., Feizi T.
SourceJ. Biol. Chem. 266:5552-5557(1991).

PROSITE is copyright. It is produced by the SIB Swiss Institute Bioinformatics. There are no restrictions on its use by non-profit institutions as long as its content is in no way modified. Usage by and for commercial entities requires a license agreement. For information about the licensing scheme send an email to
Prosite License or see: prosite_license.html.


View entry in original PROSITE document format
View entry in raw text format (no links)