- Yeast Ysl2p, homologous to Sec7 domain guanine nucleotide exchange factors, functions in endocytosis and maintenance of vacuole integrity and interacts with the Arf-Like small GTPase Arl1p. Jochum, A., Jackson, D., Schwarz, H., Pipkorn, R., Singer-Krüger, B. Mol. Cell. Biol. (2002)