Cis4 is a CDF-family zinc transporter that forms a heteromeric complex with Zrg17 in the cis-Golgi membrane. It transfers zinc from the cytosol into the secretory pathway, particularly under zinc-limiting conditions, and thereby supports intracellular zinc balance and Golgi-dependent protein trafficking. Its compartment and low-zinc role differ from the ER zinc transporter Zhf1.
The 2008 target study identifies Cis4 localization at cis-Golgi and its interaction with Zrg17. The 2018 full-text study uses zinc-sensitive FRET sensors in defined cis4/zrg17/zhf1 mutants: Cis4/Zrg17 is important during zinc limitation; ER-localized Zhf1 is important when zinc is abundant. Thus zinc specificity is supported by target physiology rather than a generic CDF family label. The ER IEA assertion remains unresolved as a possible additional pool; no exclusion experiment establishes that Cis4 can never reside in ER.
These experiments do not establish exact transport coupling, affinity, stoichiometry or complete alternative-metal exclusion. Golgi trafficking and cell-wall phenotypes are downstream consequences of zinc partitioning, not evidence that Cis4 transports magnesium or directly assembles GPI anchors. Falcon agrees on these distinctions; its numerical phenotypes are not copied into curated fields without source verification.
Exact retained output. These are name/location claims, not emitted GO/EC predictions. CNN denotes overlap with existing supported annotation; it does not establish literal membership in the training set.
| Claim type | Verbatim output | Assessment | Evidence and interpretation |
|---|---|---|---|
| name | Zinc transporter | LSP | The correct broad name omits experimentally established cis-Golgi import with Zrg17 and its low-zinc role. Target zinc-sensor and localization experiments establish zinc specificity (PMID:18199682; PMID:29529046). |
| location | Membrane | LSP | A correct but broad compartment: the target is a cis-Golgi membrane transporter. This conclusion comes from target localization and zinc-transport physiology, not simply from a membrane-domain default (PMID:18199682; PMID:29529046). |
PMID:29529046(https://pubmed.ncbi.nlm.nih.gov/29529046/):
Cis4 and Zrg17 form a heterodimeric complex that
transports zinc into the cis-Golgi.
PMID:29529046(https://pubmed.ncbi.nlm.nih.gov/29529046/):
deletion of cis4 or
zrg17 leads to higher levels of zinc accumulating in the cytosol under
conditions of zinc deficiency
The genuine Falcon report is retained with its provider metadata and artifact. Its conclusions were checked against the target record, exact accession and primary sources described above. Scientific uncertainties are recorded as UNC/UNDECIDED findings rather than a request for another reviewer to perform this assessment.