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Family of G-protein coupled receptors
Protein family
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.
Devreotes PN, Kimmel AR, Johnson RL, Klein PS, Sun TJ, Saxe III CL (1988). "A chemoattractant receptor controls development in Dictyostelium discoideum". Science. 241 (4872): 1467–1472. Bibcode:1988Sci...241.1467K. doi:10.1126/science.3047871. PMID3047871.