Integrative model of the FSH receptor reveals the structural role of the flexible hinge region

The follicle-stimulating hormone receptor (FSHR) belongs to the glycoprotein hormone receptors, a subfam-ily of G-protein-coupled receptors (GPCRs). FSHR is involved in reproductive processes such as gonadal development and maturation. Structurally, the extensive extracellular domain, which contains the hor-mone-binding site and is linked to the transmembrane domain by the hinge region (HR), is characteristic for these receptors. How this HR is involved in hormone binding and signal transduction is still an open ques-tion. We combined in vitro and in situ chemical crosslinking, disulfide pattern analysis, and mutation data with molecular modeling to generate experimentally driven full-length models. These models provide insights into the interface, important side-chain interactions, and activation mechanism. The interface indicates a strong involvement of the connecting loop. A major rearrangement of the HR seems implausible due to the tight arrangement and fixation by disulfide bonds. The models are expected to allow for testable hypotheses about signal transduction and drug development for GPHRs.

Automated summary

This study reveals the role of the hinge region in hormone binding and signal transduction of the follicle-stimulating hormone receptor through experimentally driven full-length models. Important information such as the interface, side-chain interactions, and activation mechanism is obtained by molecular modeling and chemical crosslinking.