Article ; Online: Identification of dimer interactions required for the catalytic activity of the TRPM7 alpha-kinase domain.
2009 Volume 420, Issue 1, Page(s) 115–122
Abstract: ... as residues critical for activity. Examination of the TRPM7 kinase domain structure suggests ... The activity of a monomeric TRPM7 kinase domain lacking the entire N-terminal segment was rescued by a GST ... protein kinase domain that belongs to the atypical alpha-kinase family. The TRPM7 alpha-kinase domain assembles ...
| Abstract | TRPM7 (transient receptor potential melastatin) combines an ion channel domain with a C-terminal protein kinase domain that belongs to the atypical alpha-kinase family. The TRPM7 alpha-kinase domain assembles into a dimer through the exchange of an N-terminal segment that extends from residue 1551 to residue 1577 [Yamaguchi, Matsushita, Nairn and Kuriyan (2001) Mol. Cell 7, 1047-1057]. Here, we show, by analysis of truncation mutants, that residues 1553-1562 of the N-terminus are essential for kinase activity but not dimer formation. Within this 'activation sequence', site-directed mutagenesis identified Tyr-1553 and Arg-1558 as residues critical for activity. Examination of the TRPM7 kinase domain structure suggests that the activation sequence interacts with the other subunit to help position a catalytic loop that contains the invariant Asp-1765 residue. Residues 1563-1570 of the N-terminal segment are critical for dimer assembly. Mutation of Leu-1564, Ile-1568 or Phe-1570 to alanine abolished both kinase activity and dimer formation. The activity of a monomeric TRPM7 kinase domain lacking the entire N-terminal segment was rescued by a GST (glutathione transferase) fusion protein containing residues 1548-1576 of TRPM7, showing that all interactions essential for activity are provided by the N-terminal segment. Activity was also restored by GST fused to the N-terminal segment of TRPM6 (residues 1711-1740), demonstrating the feasibility of forming functional TRPM6-TRPM7 alpha-kinase domain heterodimers. It is proposed that covalent modifications or binding interactions that alter the conformation of the N-terminal exchanged segment may provide a means to regulate TRPM7 kinase activity. |
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| MeSH term(s) | Amino Acid Sequence ; Animals ; Catalysis ; Mice ; Protein Kinases/metabolism ; Protein Multimerization ; Protein Structure, Tertiary ; Protein Subunits ; TRPM Cation Channels/chemistry ; TRPM Cation Channels/metabolism | |||||
| Chemical Substances | Protein Subunits ; TRPM Cation Channels ; Protein Kinases (EC 2.7.-) ; Trpm7 protein, mouse (EC 2.7.1.-) | |||||
| Language | English | |||||
| Publishing date | 2009-04-28 | |||||
| Publishing country | England | |||||
| Document type | Journal Article ; Research Support, Non-U.S. Gov't | |||||
| ZDB-ID | 2969-5 | |||||
| ISSN | 1470-8728 ; 0006-2936 ; 0306-3275 ; 0264-6021 | |||||
| ISSN (online) | 1470-8728 | |||||
| ISSN | 0006-2936 ; 0306-3275 ; 0264-6021 | |||||
| DOI | 10.1042/BJ20081405 | |||||
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| Database | MEDical Literature Analysis and Retrieval System OnLINE |
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