Abstract
Plasma membrane intrinsic proteins (PIPs) can be divided into two major groups, PIP1s and PIP2s, on the basis of their sequence. All PIP2s exhibit high water-channel activity in Xenopus oocytes or in yeast vesicles, whereas PIP1s are often inactive or have low activity. Since the level of PIP1s protein is much lower than that of PIP2s, and PIP1s fail to target the plasma membrane in Xenopus oocytes, there have been a question whether PIP1 molecules themselves are inactive or not. Co-expression of HvPIP1;2 and HvPIP2;4 genes in Xenopus oocytes demonstrated a positive cooperative effect in aquaporin activity and the contribution of HvPIP1;2 in the activity (Shibasaka and Katsuhara, 2009). In this study we made a chimera protein (HvPIP1;2N2C2) derived from HvPIP1;2 which can alone target the plasma membrane of Xenopus oocytes. Using this chimera protein as an escort for the PIP1 protein to the plasma membrane demonstrated that PIP1 molecule without PIP2 molecule had no water-channel activity. This work was supported by the Program for Promotion of Basic Research Activities for Inovative Biosciences (PROBRAIN).
