Putative farnesyl binding site at the cytoplasmic core of rhodopsin. (A) Structure of light-activated rhodopsin bound to a C-terminal Gt α peptide (yellow; PDB accession no. 3DQB), with the αB and αC helices of EH₂ (orange) from Eps15 bound to the STNPFR peptide (blue) manually aligned with TM1 and H8 (reddish-purple) of rhodopsin. (B) Closeup of A showing critical side chains; the NPF containing peptide is a model of how the NPF motif of Gγ may interact with GPCRs. (C) Alignment of three residues, SLE, in the αC helix of EH₂ domain with NKQ of H8 in rhodopsin (grey boxes). Interactions of SLE with the STNPFR peptide and NKQ with H5 of Gt α are indicated with black lines. PyMOL was used to determine interactions as contacts <4 Å.