Protein Wingless (wg) Drosophila Melanogaster Recombinant Protein

Function: Binds as a ligand to a family of frizzled seven-transmembrane receptors and acts through a cascade of genes on the nucleus. Segment polarity protein. May be a growth factor. Acts on neighboring cells to regulate at least one gene, the homeobox segmentation gene engrailed. Wg signal represses arm phosphorylation. Wg signaling operates by inactivating the sgg repression of engrailed autoactivation. Wg and Wnt2 have a role in the developing trachea and together are responsible for all dorsal trunk formation. Wg also acts in the developing epidermis. Acts as a morphogen, and diffuses long distances despite its lipidation. Lipophorin is required for diffusion, probably by acting as vehicle for its movement, explaining how it can spread over long distances despite its lipidation. In non-neuronal cells, wls directs wg secretion via clathrin-mediated endocytosis and the retromer complex (a conserved protein complex consisting of Vps26 and Vps35) to sustain a wls traffic loop encompassing the Golgi, the cell surface, an endocytic compartment and a retrograde route leading back to the Golgi. In neuronal cells (the larval motorneuron NMJ), wg signal moves across the synapse through the release of wls-containing exosome-like vesicles. Ref.11 Ref.15 Ref.16 Ref.17

Subunit structure: Monomer; folds by intramolecular disulfide bonds. Interacts with porcupine (por). Interacts with wls; in the Golgi. Ref.8 Ref.12 Ref.15

Subcellular location: Secreted. Cell junction › synapse. Membrane; Lipid-anchor. Secreted › extracellular space › extracellular matrix. Note: Palmitoylation converts wg into a membrane-anchored protein that is partitioned into specialized lipid raft microdomains before secretion. Possibly associated with the extracellular matrix. Ref.3 Ref.13 Ref.15 Ref.17

Tissue specificity: Segmented expression in embryos. In embryonic tracheal cells, expression is in stripes flanking the tracheal placode. Ref.1 Ref.11

Developmental stage: Expressed throughout development, but barely detectable in adults. Ref.1 Ref.2

Post-translational modification: Palmitoylated by porcupine, acylation is a prerequisite. The lipid group functions as a sorting signal, targeting the ligand to polarized vesicles that transport wg to unique sites at the cell surface. Major form is glycosylated at 2 sites, glycosylation is stimulated by porcupine at the ER, again acylation is a prerequisite. Ref.12

Disruption phenotype: Accumulation in the Golgi, thereby preventing secretion. Ref.16

Sequence similarities: Belongs to the Wnt family.