The WIPI (WD-repeat proteins Interacting with PhosphoInositides) protein family is an evolutionarily highly conserved 7-bladed beta-propeller protein family, commonly binding to particular phosphoinositides, PtdIns(3)P (phosphatidylinositol 3-phosphate) and PtdIns(3,5)P2 (phosphatidylinositol 3,5-bisphosphate) (Proikas-Cezanne et al. 2004). Yeast (Atg18) and human (WIPI-1, WIPI-2, WIPI-4) members have been found to function as essential phosphoinositide effectors in autophagy (Stromhaug et al. 2004; Proikas-Cezanne et al. 2007), a lysosomal degradation mechanism that secures cellular survival in both normal and tumor cells (Mizushima et al. 2008). The specific localization of WIPI-1 at autophagosomal membranes is used to monitor the process of autophagy in cancer cells (Proikas-Cezanne and Pfisterer 2009).
Ancient 7-bladed beta-propeller protein family with two paralogous groups, one...