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cryo-EM structure of calcineurin-fused beta2 adrenergic receptor in carazolol bound inactive state
Structural highlights
FunctionADRB2_HUMAN Beta-adrenergic receptors mediate the catecholamine-induced activation of adenylate cyclase through the action of G proteins. The beta-2-adrenergic receptor binds epinephrine with an approximately 30-fold greater affinity than it does norepinephrine.CANB1_HUMAN Regulatory subunit of calcineurin, a calcium-dependent, calmodulin stimulated protein phosphatase. Confers calcium sensitivity. Publication Abstract from PubMedAdvances in singe-particle cryo-electron microscopy (cryo-EM) have made it possible to solve the structures of numerous Family A and Family B G protein-coupled receptors (GPCRs) in complex with G proteins and arrestins, as well as several Family C GPCRs. Determination of these structures has been facilitated by the presence of large extramembrane components (such as G protein, arrestin, or Venus flytrap domains) in these complexes that aid in particle alignment during the processing of the cryo-EM data. In contrast, determination of the inactive state structure of Family A GPCRs is more challenging due to the relatively small size of the seven transmembrane domain (7TM) and to the surrounding detergent micelle that, in the absence of other features, make particle alignment impossible. Here, we describe an alternative protein engineering strategy where the heterodimeric protein calcineurin is fused to a GPCR by three points of attachment, the cytoplasmic ends of TM5, TM6, and TM7. This three-point attachment provides a more rigid link with the GPCR transmembrane domain that facilitates particle alignment during data processing, allowing us to determine the structures of the beta(2) adrenergic receptor (beta(2)AR) in the apo, antagonist-bound, and agonist-bound states. We expect that this fusion strategy may have broad application in cryo-EM structural determination of other Family A GPCRs. Calcineurin-fusion facilitates cryo-EM structure determination of a Family A GPCR.,Xu J, Chen G, Wang H, Cao S, Heng J, Deupi X, Du Y, Kobilka BK Proc Natl Acad Sci U S A. 2024 Nov 26;121(48):e2414544121. doi: , 10.1073/pnas.2414544121. Epub 2024 Nov 20. PMID:39565314[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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