A new article, Drug and peptide transport in humans
https://proteopedia.org/w/Drug_and_peptide_transport_in_humans

includes morphs illustrating the "rocker-switch" mechanism by which integral membrane transporter proteins are believed to transport nutritional peptides (from digestion of proteins) and drugs into intestinal cells. This transport is driven by the transmembrane proton gradient.

Look down into the outward-facing channel while it opens and closes, intermittently revealing bound dipeptide.

The sizes and shapes of the outward and inward-facing open channels are visualized by filling them with pseudoatoms, which was done with the free program PACUPP, http://molviz.org/pacupp

This article is based on cryo-EM structures determined by Killer et al. in the team of Christian Löw, https://www.science.org/doi/10.1126/sciadv.abk3259

Eric Martz
http://martz.molviz.org