The study used Azo‑solubilized microsomal extraction combined with iTRAQ proteomics to identify membrane proteins whose abundance is reduced in phosphate‑limited roots of the Arabidopsis cnih5 mutant, revealing several transporters including PHT1s. Interaction of AtCNIH5 with these cargoes was confirmed via yeast split‑ubiquitin and plant tripartite split‑GFP assays, showing that AtCNIH5 operates as a low‑Pi‑responsive ER export hub that enhances growth under phosphate deficiency.