Fig. 1: Identification of Gα carboxy-tail amino acid residues that are putatively ADP-ribosylated by OZITX.

a Amino acid sequence alignment of carboxy-termini residues of heterotrimeric Gα proteins. Sequences were aligned with Clustal Omega version 1.2.4. ‘*’ represents a completely conserved residue. ‘:’ represents a conserved residue (>0.5 in the Gonnet PAM 250 matrix). ‘.’ represents a weakly conserved residue (≤0.5 and >0 in the Gonnet PAM 250 matrix). Cysteine residues ADP ribosylated by PTX are indicated in red. Putative lysine and asparagine residues ADP ribosylated by OZITX identified by Littler and colleagues²³ are indicated in yellow. The asparagine residue that is a putative substrate is conserved across many Gα subunits. b The location of OZTX’s and PTX’s substrate amino acid sites within a GPCR–G protein complex. The structure of rhodopsin bound to Gα_i1β₁γ₂ is depicted in the cartoon (PDB code 6CMO). Rhodopsin is shown in dark blue, Gα_i1 in light blue, Gβ₁ in green and Gγ₂ in light green. The carboxy-terminal Cys³⁵¹ residue ADP ribosylated by PTX is shown in red spheres. Lys³⁴⁵ and Asn³⁴⁷, the putative residues ADP ribosylated by OZITX, are highlighted in yellow spheres. Graphic constructed using UCSF chimera.