(Alliance, FBgn0001085 )

Receptor for Wnt proteins. Most of frizzled receptors are coupled to the beta-catenin canonical signaling pathway, which leads to the activation of disheveled proteins, inhibition of GSK-3 kinase, nuclear accumulation of beta-catenin and activation of Wnt target genes. A second signaling pathway involving PKC and calcium fluxes has been seen for some family members, but it is not yet clear if it represents a distinct pathway or if it can be integrated in the canonical pathway, as PKC seems to be required for Wnt-mediated inactivation of GSK-3 kinase. Both pathways seem to involve interactions with G-proteins. Required to coordinate the cytoskeletons of epidermal cells to produce a parallel array of cuticular hairs and bristles.

(UniProt, P18537)

Hairs on thorax directed irregularly toward midline. Thoracic bristles also inturned and often wavy. Postverticals may turn outward. Hairs on wing edge and feet nearly erect; trichomes on wings of flies carrying weaker alleles tend to form swirls rather than lying parallel to one another and pointing distally; stronger alleles can cause random orientation of trichomes. Polarity of chaetae deranged in characteristic ways on wings, notum, halteres, legs, tergites, and sternites; fz M+ clones in M/+ wings cause derangement of polarity in M/+ cells surrounding clone (Gubb and Garcia-Bellido, 1982, J. Embryol. Exp. Morphol. 68: 37-57). In a wild-type background clones of wing cells homozygous for fz alleles that cause eye roughening, but not of those without effect on eye texture, cause adjacent normal trichomes in regions distal, anterior, and posterior, but not proximal to the clone, to orient toward the clone rather than distally as they normally do; no effect on trichomes on opposite surface of the wing (Vinson and Adler, 1987, Nature 329: 549-51). Wing may be reduced. A low level of doubling of trichomes and splitting of chaetae observed. Sex combs may be irregular. Most alleles cause eyes to be rough. Two weak alleles, fz24 and fz34 and two neomorphic alleles, fz13 and fz20, have normal eye textures. Extra leg joints tend to form as mirror-image duplications proximal to the normal joints on tarsal segments one to four. Also polarities of bristles, hairs, and bracts on legs abnormal (Held, Duarte, and Derakhshanian, 1986, Wilhelm Roux's Arch. Dev. Biol. 195: 145-57). RK2.

A neomorphic allele causing severe disruption of trichome orientation in the costal wing cell, a region little affected by most alleles; phenotype of homozygote more severe than that of hemizygote. Also unlike other alleles, homozygous clones of fz13 cells in the wing do not affect orientation of trichomes in surrounding normal cells. A third notable feature of fz13 is that it is without effect on eye texture.

Like fu13.