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Dissecting the functions of conserved prolines within transmembrane helices of the D2 dopamine receptor.

ABSTRACT: G protein-coupled receptors (GPCRs) contain a number of conserved proline residues in their transmembrane helices, and it is generally assumed these play important functional and/or structural roles. Here we use unnatural amino acid mutagenesis, employing ?-hydroxy acids and proline analogues, to examine the functional roles of five proline residues in the transmembrane helices of the D2 dopamine receptor. The well-known tendency of proline to disrupt helical structure is important at all sites, while we find no evidence for a functional role for backbone amide cis-trans isomerization, another feature associated with proline. At most proline sites, the loss of the backbone NH is sufficient to explain the role of the proline. However, at one site, P210(5.50), a substituent on the backbone N appears to be essential for proper function. Interestingly, the pattern in functional consequences that we see is mirrored in the pattern of structural distortions seen in recent GPCR crystal structures.

SUBMITTER: Van Arnam EB

PROVIDER: S-EPMC3199346 | biostudies-literature | 2011 Oct

REPOSITORIES: biostudies-literature

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Dissecting the functions of conserved prolines within transmembrane helices of the D2 dopamine receptor.

Van Arnam Ethan B EB Lester Henry A HA Dougherty Dennis A DA

ACS chemical biology 20110728 10

G protein-coupled receptors (GPCRs) contain a number of conserved proline residues in their transmembrane helices, and it is generally assumed these play important functional and/or structural roles. Here we use unnatural amino acid mutagenesis, employing α-hydroxy acids and proline analogues, to examine the functional roles of five proline residues in the transmembrane helices of the D2 dopamine receptor. The well-known tendency of proline to disrupt helical structure is important at all sites, ...[more]

PMID: 21776983

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Project description:Functional selectivity (or biased agonism) is a property exhibited by some G protein-coupled receptor (GPCR) ligands, which results in the modulation of a subset of a receptor's signaling capabilities and more precise control over complex biological processes. The dopamine D2 receptor (D2R) exhibits pleiotropic responses to the biogenic amine dopamine (DA) to mediate complex central nervous system functions through activation of G proteins and β-arrestins. D2R is a prominent therapeutic target for psychological and neurological disorders in which DA biology is dysregulated and targeting D2R with functionally selective drugs could provide a means by which pharmacotherapies could be developed. However, factors that determine GPCR functional selectivity in vivo may be multiple with receptors, ligands and transducers contributing to the process. We have recently described a mutagenesis approach to engineer biased D2R mutants in which G protein-dependent ([Gprot]D2R) and β-arrestin-dependent signaling ([βarr]D2R) were successfully separated (Peterson, et al. PNAS, 2015). Here, permutations of these mutants were used to identify critical determinants of the D2R signaling complex that impart signaling bias in response to the natural or synthetic ligands. Critical residues identified in generating [Gprot]D2R and [βarr]D2R conferred control of partial agonism at G protein and/or β-arrestin activity. Another set of mutations that result in G protein bias was identified that demonstrated that full agonists can impart unique activation patterns, and provided further credence to the concept of ligand texture. Finally, the contributions and interplay between different transducers indicated that G proteins are not aberrantly activated, and that receptor kinase and β-arrestin activities are inextricably linked. These data provide a thorough elucidation of the feasibility and malleability of D2R functional selectivity and point to means by which novel in vivo therapies could be modeled.

Dataset Information

Dissecting the functions of conserved prolines within transmembrane helices of the D2 dopamine receptor.

Publications

Dissecting the functions of conserved prolines within transmembrane helices of the D2 dopamine receptor.

Similar Datasets

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