Abstract
Plasma membrane intrinsic protein is classified into two subfamilies, PIP1 and PIP2. The activities when co-expressing PIP1 and PIP2 were higher than sum of those when PIP1 and PIP2 expressing separately. It's thought that protein traffic and heterotetramer formation participate in this activation mechanism. Previous data of X-ray structural analysis of PIP2 tetramer showed that twenty and a few amino acid residues contribute to adhesion between neighboring monomers and most of them are located in transmembrane helices. Peptide sequence of the transmembrane domain of PIPs is so conservative that mixed complex with PIP1 and PIP2 is presumed to be able to form. As for protein traffic, a series of experiment using chimeric proteins of which N-terminal was exchanged showed that a peptide sequence which is needed for PIP2 protein to target to the plasmamembrane is located in the N-terminal. Determining the peptide sequence pattern of the motif is being continued.
