Galectins are proteins that like to bind to β-galactoside sugars.  The Ga in Ga-Lectin refers to Galactose and Lectin refers to protein.  So it follows Galectins are proteins that have an affinity for sugar or carbohydrates.  What’s interesting about Galectins is that they are soluble proteins responsible for Cellular and Intracellular functions.  Most Lectins are found on a cell membranes surface but Galectins can be found inside and outside the cell.  Galectins have been identified in humans and animals.  Approximately 15 Galectins have been discovered.  The ones predominantly found in humans are the Gal -1,-2,-3,-4,-7,-8,-10,-12,-13.

The focus of much research is on the following Galectins
Galectin-1 – They are secreted by immune cells like the T Helper Cells called CD4+ cells.   presence of this Galectin in HIV has been know to accelerate HIV infection.  They are found in muscle, neurons and kidneys.
Galectin-2 – These Galectins are located primarily in the GI tract
Galectin-3 – These Galectins are of the most importance because in their role of regulating the TCells ability to produce cytotoxins.
Galectin-4 – Primarily found in the stomach and intestines and they like to bind with proteins.  They are responsible for delivering proteins to cells and there is a link to them in Inflammatory Bowel Disease.
Galectin-7 – This Galectin has a key role in regulating the apoptosis of skin cells after DNA damage caused by UV radiation.
Galectin-9 – Found in the Kidney, Thymus and Synovial fluid around joints.  The galectin promotes the maturation of dendrite cells that secrete the inflammatory cytokines linked to Rheumatoid arthritis.
Galectin-12 – Expression of this Galectin induces apoptosis of adipocytes.   Adipocytes are basically fat cells that store energy.  In the presence of Gal-12 fat cells are targeted to be destroyed.