Cyclic AMP receptors

Cyclic AMP receptors from slime molds are a distinct family of 
G-protein coupled receptors. These receptors control development in
Dictyostelium discoideum.
In "D. discoideum", the cyclic AMP receptors coordinate aggregation of individual cells into a multicellular organism, and regulate the expression of a large number of developmentally-regulated genes. The amino acid sequences of the receptors contain high proportions of hydrophobic residues grouped into 7 domains, in a manner reminiscent of the rhodopsins and other receptors believed to interact with G-proteins. However, while a similar 3D framework has been proposed to account for this, there is no significant sequence similarity between these families: the cAMP receptors thus bear their own unique '7TM' signature.