Functions in the anterograde transport of storage protein precursors from the endoplasmic reticulum (ER) to the Golgi complex and in the retrograde transport from the Golgi complex to the ER (PubMed:17194767, PubMed:23025793). Forms a complex with ZW10/MIP1, MIP2 and MIP3 on the ER that may be responsible for efficient transport of seed storage proteins (PubMed:24118572). Required for the responses to environmental stresses during seed germination and vegetative growth. Probably not involved in the retrograde transport from the ER to the apoplast (PubMed:23025793). Interacts with SEC20 and SYP81 (PubMed:17194767). Interacts with ZW10 (via the central region) (PubMed:23025793). Forms a complex with ZW10/MIP1, MIP2 and MIP3 on the endoplasmic reticulum (PubMed:24118572). Highly expressed in dry seeds. Expressed at low levels in roots, rosette and cauline leaves, stems and flowers. By salt and osmotic stresses. No visible phenotype under normal growth conditions, but dry seeds of mutant plants accumulate the precursors of the two major storage proteins albumin 2S and globulin 12S (PubMed:17194767). Increased sensitivity to salt stress, osmotic stress and abscisic acid (ABA) during germination and vegetative growth (PubMed:23025793). Belongs to the RINT1 family.