Figure 1.
Figure 1: Schematic diagram of the topology of squid rhodopsin.
-Helices
are denoted by black rectangles, 3[10] helices as grey
rectangles and -strands
as open arrows. In the current structural model, the polypeptide
chain is traced from Glu 9 to Glu 358 (shown by black letters).
Grey letters indicate residues that are truncated or disordered.
Retinal bound to Lys 305 and palmitoyl bound to Cys 337 are
included in the structural model. A disulphide bond is formed
between Cys 108 and Cys 186. The counterion Glu 180, residues
within 3.5 Å of the Schiff base and within 4 Å of
the retinal polyene chain are circled by red, purple and green
lines, respectively. Positively and negatively ionizable
residues are marked with blue and pink circles, respectively.
-Helices
are denoted by black rectangles, 3[10] helices as grey
rectangles and 
-strands
as open arrows. In the current structural model, the polypeptide
chain is traced from Glu 9 to Glu 358 (shown by black letters).
Grey letters indicate residues that are truncated or disordered.
Retinal bound to Lys 305 and palmitoyl bound to Cys 337 are
included in the structural model. A disulphide bond is formed
between Cys 108 and Cys 186. The counterion Glu 180, residues
within 3.5 Å of the Schiff base and within 4 Å of
the retinal polyene chain are circled by red, purple and green
lines, respectively. Positively and negatively ionizable
residues are marked with blue and pink circles, respectively.