© 2005 The Japanese Biochemical Society.
Regular Paper |
Characterization of the Protein Phosphatase 1–Binding Motifs of Inhibitor-2 and DARPP-32 by Surface Plasmon Resonance
1 Institute of Biochemistry and Molecular Biology and 2 Structural Biology Program, National Yang-Ming University, Taipei 11221, Taiwan, ROC; 3 Department of Medical Research & Education, Taipei Veterans General Hospital, Taipei 11217, Taiwan, ROC; 4 Institute of Molecular Biology, National Chung Cheng University, Chia-Yi 621, Taiwan, ROC; 5 Department of Research, Buddhist Chi Tzu General Hospital, Hualien 970, Taiwan, ROC; and 6 Department of Medical Technology, Chi Tzu University, Hualien 970, Taiwan, ROC
* To whom correspondence should be addressed. Fax: +886-5-272-2871, E-mail: biohbh{at}ccu.edu.tw
KLHY is a short amino-acid sequence of inhibitor-2. This sequence is highly conserved with the protein phosphatase 1 (PP1)–binding consensus motif, RVXF. The role of this segment in binding with PP1 is ambiguous. By using surface plasmon resonance we have characterized its binding ability to PP1. Either site-directed mutagenesis or deletion of KLHY did not significantly affect the dissociation constant between PP1 and inhibitor-2. In comparison with DARPP-32, the deletion of KKIQF, a PP1-binding motif of DARPP-32, resulted in a remarkable reduction in its affinity with PP1. Our results suggested that, compared with the common RVXF motif, the KLHY sequence in intact inhibitor-2 binds weakly to PP1.