Protein Ser/Thr phosphatases PPEF interact with calmodulin

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• 作者：Kutuzov ; Mikhail A. ; Solov'eva ; Olga V. ; Andreeva ; Alexandra V. ; Bennett ; Nelly
• 关键词：Protein phosphorylation ; Protein Ser/Thr phosphatase ; Calmodulin ; rdgC/PPEF ; Yeast two-hybrid system ; Surface plasmon resonance
• 刊名：Biochemical and Biophysical Research Communications
• 出版年：2002
• 出版时间：May 10, 2002
• 年：2002
• 卷：293
• 期：3
• 页码：1047-1052
• 全文大小：247 K

文摘

Regulation of protein dephosphorylation by cytoplasmic Ca²⁺ levels and calmodulin (CaM) is well established and considered to be mediated solely by calcineurin. Yet, recent identification of protein phosphatases with EF-hand domains (PPEF/rdgC) point to the existence of another group of Ca²⁺-dependent protein phosphatases. We have recently hypothesised that PPEF/rdgC phosphatases might possess CaM-binding sites of the IQ-type in their N-terminal domains. We now employed yeast two-hybrid system and surface plasmon resonance (SPR) to test this hypothesis. We found that entire human PPEF2 interacts with CaM in the in vivo tests and that its N-terminal domain binds to CaM in a Ca²⁺-dependent manner with nanomolar affinity in vitro. The fragments corresponding to the second exons of PPEF1 and PPEF2, containing the IQ motifs, are sufficient for specific Ca²⁺-dependent interaction with CaM both in vivo and in vitro. These findings demonstrate the existence of mammalian CaM-binding protein Ser/Thr phosphatases distinct from calcineurin and suggest that the activity of PPEF phosphatases may be controlled by Ca²⁺ in a dual way: via C-terminal Ca²⁺-binding domain and via interaction of the N-terminal domain with CaM.