In yeast, Yos1 is a subunit of the Yip1p-Yif1p complex and is required for transport between the endoplasmic reticulum and the Golgi complex []. This entry also includes animal IER3IP1 (immediate Early Response 3 Interacting Protein 1), which is localized to the endoplasmic reticulum. Mutations in the IER3IP1 gene cause permanent neonatal diabetes mellitus in human [].