6co7
Structure of the nvTRPM2 channel in complex with Ca2+
Structural highlights
FunctionTMP2L_NEMVE Nonselective, voltage-independent cation channel that mediates Ca(2+) and to a lesser extent Na(+) influx, leading to increased cytoplasmic Ca(2+) levels (PubMed:25620041, PubMed:27333281, PubMed:28775320, PubMed:29745897). Functions as a ligand-gated ion channel (PubMed:25620041, PubMed:27333281, PubMed:28775320, PubMed:29745897). Binding of ADP-ribose causes a conformation change; the channel is primed but still requires Ca(2+) binding to trigger channel opening (PubMed:25620041, PubMed:27333281, PubMed:28775320, PubMed:29745897). May have ADP-ribose pyrophosphatase activity which reduces ADP-ribose levels induced by oxidative stress, thus preventing the channel activation by reactive oxygen species (PubMed:25620041, PubMed:27333281).[1] [2] [3] [4] Publication Abstract from PubMedTransient Receptor Potential Melastatin 2 (TRPM2) is a Ca(2+)-permeable cation channel required for immune cell activation, insulin secretion, and body heat control. TRPM2 is activated by cytosolic Ca(2+), phosphatidyl-inositol-4,5-bisphosphate and ADP ribose. Here we present the ~3A resolution electron cryo-microscopy structure of TRPM2 from Nematostella vectensis, 63% similar in sequence to human TRPM2, in the Ca(2+)-bound closed state. Compared to other TRPM channels, TRPM2 exhibits unique structural features that correlate with its function. The pore is larger and more negatively charged, consistent with its high Ca(2+) selectivity and larger conductance. The intracellular Ca(2+) binding sites are connected to the pore and cytosol, explaining the unusual dependence of TRPM2 activity on intra- and extracellular Ca(2+). In addition, the absence of a post-filter motif is likely the cause of the rapid inactivation of human TRPM2. Together, our cryo-EM and electrophysiology studies provide a molecular understanding of the unique gating mechanism of TRPM2. Structure of a TRPM2 channel in complex with Ca(2+) explains unique gating regulation.,Zhang Z, Toth B, Szollosi A, Chen J, Csanady L Elife. 2018 May 10;7. pii: 36409. doi: 10.7554/eLife.36409. PMID:29745897[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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