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 , which is composed of two galectin domains.
Galectin-7 , a keratinocyte protein which could be involved in cell-cell
and/or cell-matrix interactions necessary for normal growth control.
Galectin-8 , which is composed of two galectin domains.
Galectin-9 , which is composed of two galectin domains.
Human eosinophil lysophospholipase (EC 188.8.131.52)  (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 . This lectin is
composed of two galectin domains.
Caenorhabditis elegans lec-7 and lec-8.
The profile we developed covers the entire galectin domain.
March 2007 / Pattern removed, profile added and text revised.
PROSITE method (with tools and information) covered by this documentation:
Introduction to galectins.;
Trends Glycosci. Glycotechnol. 9:9-19(1997).
Leffler H. Carlsson S. Hedlund M. Qian Y. Poirier F.
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