COPIflutning

COPIflutning is a hypothetical term used in cell biology to describe a subset of retrograde transport events within the secretory pathway. The concept refers to COPI-coated carriers that are proposed to mediate not only traditional vesicular transport from the Golgi to the endoplasmic reticulum but also dynamic, tubule‑mediated flux within the Golgi stack and between cisternae. The name combines the coatomer protein complex I (COPI) with a root meaning transport or flow, reflecting an emphasis on flexible carrier morphologies.

Mechanism and components are described in proposed models as beginning with ARF1 activation and coatomer recruitment to Golgi membranes, followed by the formation of elongated tubular carriers that extend along cisternal surfaces, constrict, and bud off. Cargo selection involves sorting signals recognized by coatomer subunits and stabilizing tethering factors; subsequent uncoating and fusion with target membranes are mediated by SNAREs and Rab GTPases. The process is thought to interface with canonical COPI trafficking and may operate in concert with, or as a specialization of, vesicular transport.

Evidence and status: COPIflutning appears in theoretical discussions and in a subset of advanced imaging studies reporting tubular COPI‑like structures. Its interpretation as a distinct transport pathway is debated; some researchers view the observations as artefacts or variations of established COPI budding, while others advocate for its functional relevance in specific cellular states. More genetic and biochemical data are needed to confirm its prevalence and significance.

Significance: If validated, COPIflutning would refine understanding of Golgi organization, cargo flow, and the regulation of glycosylation and lipid transport during cellular stress. See also COPI vesicles, ARF1, SNAREs, Golgi apparatus.