TRP and Rhodopsin Transport Depends on Dual XPORT ER Chaperones Encoded by an Operon

Zijing Chen, Hsiang Chin Chen, Craig Montell

Research output: Contribution to journalArticlepeer-review

Abstract

TRP channels and G protein-coupled receptors (GPCRs) play critical roles in sensory reception. However, the identities of the chaperones that assist GPCRs in translocating from the endoplasmic reticulum (ER) are limited, and TRP ER chaperones are virtually unknown. The one exception for TRPs is Drosophila XPORT. Here, we show that the xport locus is bicistronic and encodes unrelated transmembrane proteins, which enable the signaling proteins that initiate and culminate phototransduction, rhodopsin 1 (Rh1) and TRP, to traffic to the plasma membrane. XPORT-A and XPORT-B are ER proteins, and loss of either has a profound impact on TRP and Rh1 targeting to the light-sensing compartment of photoreceptor cells. XPORT-B complexed in vivo with the Drosophila homolog of the mammalian HSP70 protein, GRP78/BiP, which, in turn, associated with Rh1. Our work highlights a coordinated network of chaperones required for the biosynthesis of the TRP channel and rhodopsin in Drosophila photoreceptor cells. Rhodopsin and TRP are signaling proteins that initiate and culminate Drosophila phototransduction. Chen et al. show that the xport locus is bicistronic and encodes two distinct chaperones, both of which are essential for TRP and rhodopsin to exit the endoplasmic reticulum and insert into rhabdomeres.

Original languageEnglish (US)
Article number2070
JournalCell Reports
Volume13
Issue number3
DOIs
StatePublished - Oct 20 2015
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)

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