LGALS3 LGALS3 (lectin, galactoside-binding, soluble 3 [galectin 3]), Mac-2,
Molecule TypeAntigen ExpressionMolecular Weight
Min / Max
Non-lineage Restricted Molecule
Carbohydrate
Macrophage
Epithelium

Expression
LGALS3 is expressed at high elevels in activated macrophages and on thioglycollate-elicited macrophages at 1.7 x 10 to the 5th sites.  A major expression is found in colonic epithelium.  It is likely that cell surface expression is due to the carbohydrate recognition domain binding to cell surface glycoproteins as surface expression is reduced by inhibitory sugars.

Structure
MOLECULAR FAMILY NAME: Belongs to the galectin lectin family.

Galectins, S-type lectins, contain carbohydrate binding domains which have a sequence similarity in the carbohydrate binding sites and have an affinity for b-galactoside sugars.  LGALS3 is a 242 aa glycoprotein which contains 2 distinct domains. The N-terminal extracellular domain contains a rich Pro- and Gly-residues and contains multiple repeats of the sequence PGAYPG or slight variations thereof, and the C-terminal cytoplasmic domain contains the carbohydrate binding domain.  LGALS3 contains a galectin domain.  The protein contains no hydrophobic sequences that may function as signal sequences or transmembrane domains and is secreted by unknown mechanisms. LGALS3 can form multimers through its N-terminal domain and this is not dependent on disulfide formation.  LGALS3 probably forms homo- or heterodimers.

MOLECULAR MASS
Cell Type Unreduced Reduced
35 kDa, 67 kDa, 80 kDa 35 kDa

POST-TRANSCRIPTIONAL MODIFICATION: No information.

POST-TRANSLATIONAL MODIFICATION: No information.

Ligands
LIGANDS AND MOLECULES ASSOCIATED WITH LGALS3

LGALS3 binds IgE and FceRI.  Another ligand is a secreted glycoprotein, Mac-2 binding protein, which contains a scavenger receptor cysteine-rich domain.  Binding activities can be inhibited by galactose.

Function
A role for LGALS3 in the crosslinking IgE receptors is postulated. It is the major non-integrin laminin binding protein of inflammatory macrophages and an anti-adhesive role is suggested. A recent study describes the activation of neutrophils by recombinant LGALS3 which is dependent on both its lectin binding activity and the N-terminal region. An intracellular role for has been suggested based on localization of the protein in the nucleus. There is evidence for LGALS3 as a factor in RNA splicing.  Activity was carbohydrate-dependent, in contrast to a report describing RNA binding by galectin.

BIOCHEMICAL ACTIVITY: No information.

DISEASE RELEVANCE AND FUNCTION OF LGALS3 IN INTACT ANTIMAL

Deregulated expression of LGALS3 can result in tumor transformation and invasiveness or confer propensity for tumor cell survival.    LGALS3 may be a potential marker of malignancy in thyroid neoplasms and may play a role in the process of metastasis in lung cancer.

Comments
MOLECULAR INTERACTION-
PROTEINS AND DNA ELEMENTS WHICH REGULATE TRANSCRIPTION OF LGALS3: No information.

SUBSTRATES: No information.

ENZYMES WHICH MODIFY LGAL3: No information.

Database accession numbers
AnimalPIRSWISSPROTEMGBL/GENBANK
 
HumanEntrezgene 6563P17931
MouseA28651P16110X16834
RatA23148P08699J02962
Antibodies

Revised June 25, 2008


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