Rhodopsin chemokine similarity

Crystal structures of GPCRs have shown that Class A receptors contain an amphi-pathic Hx8 that runs parallel to the membrane. The crystal structure of squid rhodopsin has shown an additional cytoplasmic Hx9 that interacts with TM6 (Figure 2.1b). The presence in chemokine receptors of the Phe side chain at position 8.50, conserved in 68% of Class A GPCR sequences, suggests a similar Hx8 as found in the crystal structures. Finally, it has been shown that a cyteine residue at the carboxyl-terminal domain of CCR5 is palmitoylated [40]. 

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