CASEIN KINASE-2 ASSOCIATES WITH AND PHOSPHORYLATES DISHEVELLED

The dishevelled (dsh) gene of Drosophila melanogaster encodes a phosph oprotein whose phosphorylation state is elevated by Wingless stimulati on, suggesting that the phosphorylation of Dsh and the kinase(s) respo nsible for this phosphorylation are integral parts of the Wg signaling pathway, We found that immunoprecipitated Dsh protein from embryos an d from cells in tissue culture is associated with a kinase activity th at phosphorylates Dsh in vitro, Purification and peptide sequencing of a 38 kDa protein co-purifying with this kinase activity showed it to be identical to Drosophila Casein Kinase 2 (CK2), Tryptic phosphopepti de mapping indicates that identical peptides are phosphorylated by CK2 in vitro and in vivo, suggesting that CK2 is at least one of the kina ses that phosphorylates Dsh. Overexpression of Dfz2 a Wingless recepto r, also stimulated phosphorylation of Dsh, Dsh-associated kinase activ ity, and association of CK2 with Dsh, thus suggesting a role for CK2 i n the transduction of the Wg signal.