부산대학교 도서관

PPM [metal-dependent protein phosphatase, formerly called PP2C (protein phosphatase 2C)] family members play essential roles in regulating a variety of signalling pathways. While searching for protein phosphatase(s) that act on AMPK (AMPactivated protein kinase), we found that PPM1A and PPM1B are N-myristoylated and that this modification is essential for their ability to dephosphorylate the a subunit of AMPK (AMPKa) in cells. N-Myristoylation was also required for two other functions of PPM1A and PPM1B in cells. Although a nonmyristoylated mutation (G2A) of PPM1A and PPM1B prevented membrane association, this relocalization did not likely cause the decreased activity towards AMPKa. In in vitro experiments, the G2A mutants exhibited reduced activities towards AMPKa, but much higher specific activity against an artificial substrate, PNPP (p-nitrophenyl phosphate), compared with the wild-type counterparts. Taken together, the results of the present study suggest that N-myristoylation of PPM1A and PPM1B plays a key role in recognition of their physiological substrates in cells. [ABSTRACT FROM AUTHOR]