Figure 22.

(A) Schematic of the chimera receptor designs. CCR5^QTY’s seven-transmembrane regions (yellow) and IC loops were chosen as the backbone of designs. In Chimera A (bottom left) the three EC loops of CCR5^QTY were replaced by GS linkers (red) with the same lengths (upper, yellow loops), but CCR5^QTY’s N-terminus (yellow line) was unchanged. In Chimera B (bottom right), the N-terminus and three EC loops of CCR5^QTY were replaced by those of CXCR4^QTY (green). Reprinted with permission from ref (277). Copyright 2019 National Academy of Sciences. (B) Schematic illustration of possible ligand interactions for truncated CXCR4 and CCR5 receptors. The ligand-binding motifs in the N-terminus and three EC loops are simplified and represented with cartoon blocks. Reprinted with permission from ref (279). Copyright 2020 Qing et al.