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Signaling by the Frizzled family of receptors: G protein-coupled mechanisms and
targets
Vladimir L. Katanaev
Department of Biology, University of Konstanz. Universitätsstrasse 10, Box 643.
Konstanz 78457, Germany. E-mail vladimir.katanaev@uni-konstanz.de
The Frizzled family of unconventional GPCRs transmits the signals from the developmentally
and medically important group of Wnt-type growth factors. Despite the GPCR topology of
Frizzled proteins, their functional belonging to the G protein-coupled type of receptors has
been long questioned. In the recent years, the involvement of heterotrimeric G proteins in
Frizzled signaling has been established in a number of model systems, as was the biochemical
activity of Frizzled proteins as GPCRs. Frizzled proteins from flies to humans have been
shown to couple to the Go/i type of heterotrimeric G proteins. A number of interesting targets
of G proteins in Frizzled signaling, including the scaffolding protein Axin and the small
GTPase Rab5 have been identified. These advances shed light on the mechanisms of this
intricate signal transduction cascade and identify new approaches for the anti-cancer drug
development.
Recent papers:
1. Purvanov V, Koval A, Katanaev VL. (2010) A direct and functional interaction between
the trimeric G protein Go and Rab5 in G protein-coupled receptor signaling. Sci. Signal. 3:
ra65.
2. Koval A, Katanaev VL. (2010) Wnt3a Stimulation Elicits G Protein-Coupled Receptor
Properties of Mammalian Frizzled Proteins. Biochem. J. DOI 10.1042/BJ20101878
3. Egger-Adam D, Katanaev VL. (2010) The trimeric G protein Go inflicts a double impact
on Axin in the Wnt/Frizzled signaling pathway. Dev. Dyn. 239:168–83.
4. Kopein D, Katanaev VL. (2009) Drosophila GoLoco-protein Pins is a target of G!omediated
G protein-coupled receptor signaling. Mol. Biol. Cell 20:3865-77.
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