Dear Editor,

AVP occupies an orthosteric binding pocket in the TMD bundle composed of all TM helices and ECLs (Fig. 1b, c; Supplementary information, Table S2). The most notable conformational feature of AVP is the tocin ring formed by a disulfide bridge between the first and sixth cysteine residues, presenting a “spoon-like” conformation (Supplementary information, Fig. S4a, b). The cyclic spoon head inserts deeply into the TMD core, while the C-terminal spoon tail stretches toward the ECLs of the receptor. Cys1P of AVP and Q962.61, K1163.29, Q1193.32 of V2R form a stabilizing H-bond network, consistent with the decreased potency of the receptor mutants with these residues mutated (Fig. 1b; Supplementary information, Fig. S4c, d). The hydroxyl group of Tyr2P forms an H-bonds with the main chain oxygen of L3127.40, whereas its main chain CO group forms another H-bond with Q1744.60 (Fig. 1b; Supplementary information, Fig. S4c). Phe3P buries in a hydrophobic cleft constituted by M1203.33, M1233.36, Y2055.38, V2065.39, I2095.42, F2876.51, F2886.52, and Q2916.55 (Fig. 1b; Supplementary information, Fig. S4c). Other polar contacts are seen between Gln4P and R2025.35, Gln4P and the backbone and side chain oxygens of Q2916.55, as well as Asn5P and the main chain of A194ECL2 (Fig. 1b, c; Supplementary information, Fig. S4c). Arg8P forms salt bridges with D331.28 and E401.35, the latter forms an extra salt bridge with K1002.65 (Fig. 1c; Supplementary information, Fig. S4c). Additionally, the C-terminal amide of AVP points to ECL1, stacking against the R104ECL1 guanidinium group and H-bonding to the backbone CO group of D103ECL1 (Fig. 1c; Supplementary information, Fig. S4c). These interactions between AVP and residues in V2R binding pocket were confirmed through alanine mutagenesis studies using cAMP accumulation assays (Supplementary information, Fig. S4d–g and Table S4).

Log in or create a free account to read this content

Gain free access to this article, as well as selected content from this journal and more on nature.com

Access through your institution

or

Sign in or create an account
Continue with Google
Continue with ORCiD