Fig. 4: Structural characterization of the GS•GYG2 complex.
From: Human glycogenins maintain glucose homeostasis by regulating glycogen metabolism
a Cryo-EM map of the heterotetrameric GS•GYG2 complex at 2.84 Å resolution. GS and the C-terminal domain of GYG2 (GYG2-CTD) subunits are colored separately. b–c, Structural superimposition of the GS•GYG2 complex with GS•GYG1 complex in the inhibited (b) or active (c) state. GS•GYG1 complexes are colored gray, and the color code of the GS•GYG2 complexes is as shown in (a). R.M.S.D. values are indicated. A 90o-rotated view is shown in the bottom panel. The PDB codes for GS•GYG1 complex in the inhibited and active states are 7Q0B and 7Q12, respectively. d AlphaFold3-predicted dimeric catalytic Rossmann fold domain of GYG1 (red) and GYG2 (green) across different species are superimposed, with R.M.S.D. values and manganese (Mn) indicated. The lid segment, the acceptor arm, and the C loop are highlighted. e Cartoon representation of the crystal structure of the GYG1 catalytic domain. The autoglycosylation site (Y195) and Y197 that facilitate homodimeric interaction through contacts with D160 and W128 in an adjacent molecule are depicted. f Superimposition of AlphaFold3-predicted monomeric catalytic Rossmann fold domain of human GYG1 (red) and GYG2 (green) with the C loop region is emphasized. g A zoomed-in view of the C loop region of human GYG1 (red) and GYG2 (green) highlighted by the black dashed box in f is shown. Key residues Y195 and P238 in GYG1 and their corresponding residues in GYG2 (Y228 and S271) are shown.
