Fig. 2: The three-dimensional structure of the human PAPP-A·STC2 complex. | Nature Communications

Fig. 2: The three-dimensional structure of the human PAPP-A·STC2 complex.

From: Structure of the proteolytic enzyme PAPP-A with the endogenous inhibitor stanniocalcin-2 reveals its inhibitory mechanism

Fig. 2

a SDS-PAGE separation of purified PAPP-A dimer and PAPP-A·STC2 complex used for cryo-EM analysis. Samples were reduced or non-reduced, as indicated, and the gel was stained with Coomassie brilliant blue. Active site-inactivated PAPP-A (E563Q) was used for this experiment and for further structural studies. The experiment was repeated >10 times with similar results. Source data are provided as a Source data file. b The experimental volume is shown with the final model of the 2:2 PAPP-A·STC2 complex in two orientations. Domains are colored as indicated. This color scheme is used throughout the figure. The overall approximate dimensions (W × H × D) of the PAPP-A·STC2 complex are 200 × 115 × 175 Å. c Cartoon representation of the refined PAPP-A·STC2 model in two orientations. The map (MAP2) was contoured at 4.5σ. d Schematic diagram of the covalent, heterotetrameric PAPP-A·STC2 2:2 complex, highlighting interchain cysteine connectivity.

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