EMC is required for biogenesis of Xport-A, an essential chaperone of Rhodopsin-1 and the TRP channel

Journal article

The ER membrane protein complex (EMC) is required for the biogenesis of a subset of tail anchored (TA) and polytopic membrane proteins, including Rhodopsin-1 (Rh1) and the TRP channel. To understand the physiological implications of EMC-dependent membrane protein biogenesis, we perform a bioinformatic identification of Drosophila TA proteins. From 254 predicted TA proteins, screening in larval eye discs identified two proteins that require EMC for their biogenesis: fan and Xport-A. Fan is required for male fertility in Drosophila and we show that EMC is also required for this process. Xport-A is essential for the biogenesis of both Rh1 and TRP, raising the possibility that disruption of Rh1 and TRP biogenesis in EMC mutants is secondary to the Xport-A defect. We show that EMC is required for Xport-A TMD membrane insertion and that EMC-independent Xport-A mutants rescue Rh1 and TRP biogenesis in EMC mutants. Finally, our work also reveals a role for Xport-A in a glycosylation-dependent triage mechanism during Rh1 biogenesis in the endoplasmic reticulum.

Authors: Gaspar, CJ; Vieira, LC; Santos, CC; Christianson, JC; Jakubec, D

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: EMBO Press
• Journal: EMBO Reports
• Volume: 23
• Issue: 1
• Article number: e53210
• Publication date: 2021-12-17
• Acceptance date: 2021-11-10
• DOI: 10.15252/embr.202153210
• EISSN: 1469-3178
• ISSN: 1469-221X
• Pmid: 34918864
• Language: English
• Keywords: endoplasmic reticulum; animals; Drosophila proteins; molecular chaperones; rhodopsin; repressor proteins; membrane proteins; FFR; male; basic helix-loop-helix transcription factors; Drosophila