Criteria for establishing the identity of a receptor as G-protein-coupled 2.1. Primary structure with seven transmembrane segments (7TMS) 2.2. N-and C-terminal characteristics of the receptor structure 2.3. Bacterial toxin sensitivity of the receptor-mediated pathway 2.4. Regulation by introduction of GTP analogues and/or G-protein subunits 2.5. Attenuation of receptor signaling by suppression of G-protein subunits 2.6. Mimicry of receptor signaling via introduction of activated versions of G-proteins 2.7. Agonist-specific GTP-dependent shift in receptor affinity 2.8. Functional reconstitution of purified receptors, G-proteins, and effectors 3. Frizzleds as GPCRs

3.1. Frizzled-2, regulator of Wnt/Ca++ and Wnt/cyclic GMP signaling 3.1. 1. Primary sequence of Frizzled-2 3.1. 2. N-and C-temini sequences of Frizzled-2 3.1. 3. Effects of bacterial toxins on Frizzled-2 action 3.1. 4. Injection of GTP and/or G-protein subunits on Frizzled-2 signaling 3.1. 5. Suppression of G-protein subunits and Wnt-Frizzled-2 signaling 3.1. 6. Mimicry of Frizzled-2 signaling by expression of constitutively activated Galpha subunits 3.1. 7. GTP-dependent, agonist-specific shift in Frizzled-2 affinity 3.1. 8. Functional reconstitution of the Wnt-Frizzled triad of Frizzled-2/G-protein/effector 3.1. 9. Conclusion