RT Book, Section A1 Giacomini, Kathleen M. A1 Sugiyama, Yuichi A2 Brunton, Laurence L. A2 Knollmann, Björn C. SR Print(0) ID 1193226880 T1 Membrane Transporters and Drug Response T2 Goodman & Gilman's: The Pharmacological Basis of Therapeutics, 14th Edition YR 2023 FD 2023 PB McGraw-Hill Education PP New York, NY SN 9781264258079 LK accessmedicine.mhmedical.com/content.aspx?aid=1193226880 RD 2024/10/04 AB Membrane transport proteins are present in all organisms. These proteins control the influx of essential nutrients and ions and the efflux of cellular waste, environmental toxins, drugs, and other xenobiotics (Figure 4–1). Consistent with their critical roles in cellular homeostasis, about 2000 genes in the human genome, or ~7% of the total number of genes, code for transporters or transporter-related proteins. The functions of membrane transporters may be facilitated (equilibrative, not requiring energy) or active (requiring energy). In considering the transport of drugs, pharmacologists generally focus on transporters from two major superfamilies, ABC and SLC transporters (Nigam, 2015).