5het | pdb_00005het
The third PDZ domain from the synaptic protein PSD-95 (G330T mutant)
Structural highlights
Function[DLG4_RAT] Interacts with the cytoplasmic tail of NMDA receptor subunits and shaker-type potassium channels. Required for synaptic plasticity associated with NMDA receptor signaling. Overexpression or depletion of DLG4 changes the ratio of excitatory to inhibitory synapses in hippocampal neurons. May reduce the amplitude of ASIC3 acid-evoked currents by retaining the channel intracellularly. May regulate the intracellular trafficking of ADR1B.[1] [2] Publication Abstract from PubMedProteins display the capacity for adaptation to new functions, a property critical for evolvability. But what structural principles underlie the capacity for adaptation? Here, we show that adaptation to a physiologically distinct class of ligand specificity in a PSD95, DLG1, ZO-1 (PDZ) domain preferentially occurs through class-bridging intermediate mutations located distant from the ligand-binding site. These mutations provide a functional link between ligand classes and demonstrate the principle of "conditional neutrality" in mediating evolutionary adaptation. Structures show that class-bridging mutations work allosterically to open up conformational plasticity at the active site, permitting novel functions while retaining existing function. More generally, the class-bridging phenotype arises from mutations in an evolutionarily conserved network of coevolving amino acids in the PDZ family (the sector) that connects the active site to distant surface sites. These findings introduce the concept that allostery in proteins could have its origins not in protein function but in the capacity to adapt. Origins of Allostery and Evolvability in Proteins: A Case Study.,Raman AS, White KI, Ranganathan R Cell. 2016 Jul 14;166(2):468-80. doi: 10.1016/j.cell.2016.05.047. Epub 2016 Jun, 16. PMID:27321669[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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