RNF175

Model summary

A membrane-anchored RING E3 ligase that operates at the endoplasmic reticulum and Golgi membranes to maintain proteostasis. By recruiting ubiquitin-conjugating enzymes through its RING core, it tags ER- and Golgi-traffic substrates to drive retrograde transport from the endoplasmic reticulum to the cytosol and their proteasomal clearance. This activity relieves ER stress and supports endoplasmic reticulum–associated degradation, with additional pools at the sarcoplasmic reticulum in muscle. Through controlling turnover of membrane and secretory pathway clients that influence adhesion and cytoskeletal systems, it contributes to cell migration and broader stress-responsive pathways.

Predicted Gene Ontology terms

1. 01

   I begin with the InterPro architecture.

   The sequence carries IPR040176 (RING finger protein RNF121/RNF175 family) spanning residues 15–328, marking the protein as a member of a membrane-associated RING finger cohort specialized for endoplasmic reticulum (ER) quality control. Within this family scaffold, a C-terminal zinc-binding module is evident: IPR013083 (Zinc finger, RING/FYVE/PHD-type homologous superfamily) from residues 216–289 encompasses a canonical RING core that is further specified by IPR001841 (Zinc finger, RING-type domain) at residues 227–277 and IPR018957 (Zinc finger, C3HC4 RING-type domain) at residues 238–276. The ordered layout—an N-to-C family envelope leading into a C3HC4 RING—defines a cytosolic RING E3 ligase module positioned downstream of predicted transmembrane segments typical of this family. This architecture causes robust protein-binding capacity and E2 recruitment, supporting GO:0005515 protein binding as the operative molecular function.

2. 02

   A membrane-anchored RING E3 at the ER has a well-established role in ER-associated degradation.

   The RING core catalyzes ubiquitin transfer to membrane-tethered substrates, which drives retrograde transport from ER to cytosol and subsequent proteasomal turnover. This mechanistic placement explains participation in GO:0030970 retrograde protein transport, ER to cytosol and GO:0036503 ERAD pathway. Because misfolded secretory and membrane proteins accumulate in the ER, a membrane-tethered RING E3 directly mediates the GO:0051788 response to misfolded protein and the GO:0034976 response to endoplasmic reticulum stress. The same membrane-anchored ubiquitination axis can modulate cytoskeletal and adhesion regulators that traffic through ER–Golgi routes, providing a causal route to GO:0016477 cell migration.

3. 03

   Cellular placement follows from both the membrane-tethered RING architecture and trafficking cues.

   The family signature and multi-pass topology situate the protein in the GO:0005789 endoplasmic reticulum membrane. Its role in secretory pathway surveillance and the presence of a Golgi-facing pool support localization to GO:0000139 Golgi membrane. In striated muscle, the specialized ER—sarcoplasmic reticulum—hosts intense secretory and calcium-handling functions; a membrane-anchored ERAD E3 therefore plausibly resides at GO:0033017 sarcoplasmic reticulum membrane. Together, these localizations align with a multi-pass ER/Golgi membrane E3 that orchestrates luminal and cytosolic faces of ERAD.

4. 04

   Mechanistically, the RING module recruits E2 conjugating enzymes and builds ubiquitin chains on ER-resident or ER-transiting substrates.

   This ubiquitin tagging triggers retrotranslocation and cytosolic proteasomal clearance, thereby relieving ER stress and maintaining proteostasis. By tuning the abundance of adhesion and cytoskeletal regulators that pass through ER–Golgi compartments, the protein indirectly shapes cell migration. I hypothesize that it forms transient complexes with ERAD adaptors and retrotranslocation machinery—such as SEL1L–HRD1 assemblies, Derlin channels, and p97/VCP—while also sampling substrates that influence migratory behavior. In muscle cells, the same assemblies likely interface with sarcoplasmic reticulum quality-control hubs, coupling membrane protein turnover to broader cellular homeostasis.