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

Catarina J Gaspar, Lígia C Vieira, Cristiana C Santos, John C Christianson, David Jakubec, Kvido Strisovsky, Colin Adrain, Pedro M Domingos

Research output: Contribution to journalArticlepeer-review


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.
Original languageEnglish
Article numbere53210
Number of pages16
JournalEMBO Reports
Issue number1
Early online date17 Dec 2021
Publication statusPublished - 05 Jan 2022


  • Rh1
  • TRP
  • tail anchored proteins
  • Xport-A
  • ER membrane protein complex


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