Galectin-4/6 (IPR015533)

Short name: Galectin4/6

Overlapping homologous superfamilies


Family relationships



Animal lectins are proteins that bind to sugars and are involved in most non-structural roles of sugars, including trafficking of glycoconjugates and cell-cell recognition. Although they may be structurally very complex, they typically bind through the activity of a specific compact protein domain known as a carbohydrate-binding domain or CRD [PMID: 9787635]. Animal lectins display a wide variety of architectures, and are classified according to the carbohydrate-recognition domain (CRD) of which there are two main types, S-type and C-type.

Galectins (previously S-lectins) bind exclusively beta-galactosides like lactose. They do not require metal ions for activity. Galectins are found predominantly, but not exclusively in mammals [PMID: 8124704]. Their function is unclear. They are developmentally regulated and may be involved in differentiation, cellular regulation and tissue construction. Mammalian galectins typically bind beta-galactosides. Their CRD shows a structural similarity to L-type lectin CRDs, but no strong sequence similarity, suggesting convergent evolution [PMID: 8262940]. They are classified into three subgroups: proto type, which contain one CRD (Gal-1, -2, -5, -7, -10, -11, -13, -14 and -15); tandem repeat type, which contain two CRDs in tandem (Gal-4, -6, -8, -9 and -12); and chimera type, which contain one CRD and an additional non-lectin domain (Gal-3) [PMID: 8400545, PMID: 14758066].

Although many galectins contain only one CRD and dimerise to present two CRDs per dimer, Galectin-4 and galectin-6, which are closely related (83% sequence similarity), contain two CRDs per protein and do not dimerise. Galectin-4 and -6 were initially characterised in the mouse gastrointestinal tract, and orthologs exist in many mammals [PMID: 9446608]. Galectin-4 appears to bind with high specificity to O-linked sulphoglycans [PMID: 11971864].

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.