YIF1 (Yip1 interacting factor) is an integral membrane protein that is required for membrane fusion of ER derived vesicles [1]. It also plays a role in the biogenesis of ER derived COPII transport vesicles [2].

1: The Yip1p.Yif1p complex is required for the fusion competence of endoplasmic reticulum-derived vesicles. Barrowman J, Wang W, Zhang Y, Ferro-Novick S; J Biol Chem. 2003;278:19878-19884. PMID:12657649

2: Yos1p is a novel subunit of the Yip1p-Yif1p complex and is required for transport between the endoplasmic reticulum and the Golgi complex. Heidtman M, Chen CZ, Collins RN, Barlowe C; Mol Biol Cell. 2005;16:1673-1683. PMID:15659647