N-terminal sequence alignment of different GPR83 orthologues.

The sequence alignment shows that the second half of the N-terminal tail (between positions 36–67) is particularly highly conserved among the compared variants. Therefore, the GPR83 eNDo was subdivided into two regions: 1. a low-conserved region (part 1, positions 18–35) after the signal peptide, and 2. the highly conserved region (part 2, positions 36–67). Without 3D data from structural determination of hGPR83 by crystallographic studies, the N-terminus of TMH1 is only predictable based on comparison with sequences of other family A GPCRs, where crystal structures are available (e.g., beta-adrenergic 2 receptor and rhodopsin). Different colors of amino acids indicate conservation of corresponding positions among subspecies and additionally support discrimination between their biophysical properties: green, hydrophobic; blue, positively charged; and red, negatively charged. The alignment was visualized using BioEdit.