Mu-opioid receptor biased agonism:
G protein-biased agonist (oliceridine, blue) inserts deeper in the pocket than DAMGO (unbiased, yellow), and closes the ICL1-H8 gap (lower right). This presumably inhibits arrestin signaling.
More details at:
https://doi.org/10.1016/j.molcel.2021.07.033