ACE2 and COVID-19: Coexpression evidence suggests that the small intestinal BBMV SIT1 (SLC6A20), representing the IMINO transport system serving proline uptake originally described by us,17,96,97 also functionally partners with epithelial membrane ACE2.26,98 Thus, we posit that it would be beneficial to pursue the atomic structural interactions, functional relationships, and effects of targeted drugs engaging SITS1 relating to COVID-19 in the manner analogous to B0AT1 with ACE2.