Explore the vast range of titles available.

PDZ domain mediated interactions with voltage-gated calcium (Ca V ) channel C-termini play important roles in localizing membrane Ca 2+ signaling. The first such interaction was described between the scaffolding protein Mint-1 and Ca V 2.2 in mammals. In this study, we show through various in silico analyses that Mint is an animal-specific gene with a highly divergent N-terminus but a strongly conserved C-terminus comprised of a phosphotyrosine binding domain, two tandem PDZ domains (PDZ-1 and PDZ-2), and a C-terminal auto-inhibitory element that binds and inhibits PDZ-1. In addition to Ca V 2 chanels, most genes that interact with Mint are also deeply conserved including amyloid precursor proteins, presenilins, neurexin, and CASK and Veli which form a tripartite complex with Mint in bilaterians. Through yeast and bacterial 2-hybrid experiments, we show that Mint and Ca V 2 channels from cnidarians and placozoans interact in vitro, and in situ hybridization revealed co-expression in dissociated neurons from the cnidarian Nematostella vectensis . Unexpectedly, the Mint orthologue from the ctenophore Hormiphora californiensis strongly bound the divergent C-terminal ligands of cnidarian and placozoan Ca V 2 channels, despite neither the ctenophore Mint, nor the placozoan and cnidarian orthologues, binding the ctenophore Ca V 2 channel C-terminus. Altogether, our analyses suggest that the capacity of Mint to bind Ca V 2 channels predates bilaterian animals, and that evolutionary changes in Ca V 2 channel C-terminal sequences resulted in altered binding modalities with Mint.

Neurotransmitter release relies on Ca2+ influx through voltage-gated calcium channels (CaV2), triggered by action potentials. Reliable release necessitates CaV2 localization near primed synaptic vesicles (SV). Rab3-interacting molecule (RIM) anchors CaV2 within nanometers to SVs, via interactions between the RIM PDZ domain and the C-terminus (CT; (i.e., DDWC-COOH-like motif)) of CaV2. Recently, a novel RIM paralog (RIM-II) with identical domains to the canonical RIM (RIM-I), was discovered, yet its functions remain undetermined.While this interaction is verified in vitro in mammals, I investigated its conservation in representative species across phyla. Directed Yeast 2-Hybrid screens indicated that this interaction is retained in basal-chordates, arthropods, brachiopods, and molluscs, revealing its presence in non-mammalian metazoans. Eliminating the last four residues on CaV2 CT notably reduced interactions with RIM-I PDZ domains, highlighting their importance for RIM-CaV2 interactions. However, RIM-II did not exhibit the same interactions across phyla, suggesting functional differences between RIM-I/-II PDZ domains.

PDZ domain mediated interactions with voltage-gated calcium (Ca ) channel C-termini play important roles in localizing membrane Ca signaling. The first such interaction was described between the scaffolding protein Mint-1 and Ca 2.2 in mammals. In this study, we show through various in silico analyses that Mint is an animal-specific gene with a highly divergent N-terminus but a strongly conserved C-terminus comprised of a phosphotyrosine binding domain, two tandem PDZ domains (PDZ-1 and PDZ-2), and a C-terminal auto-inhibitory element that binds and inhibits PDZ-1. In addition to Ca 2 chanels, most genes that interact with Mint are also deeply conserved including amyloid precursor proteins, presenilins, neurexin, and CASK and Veli which form a tripartite complex with Mint in bilaterians. Through yeast and bacterial 2-hybrid experiments, we show that Mint and Ca 2 channels from cnidarians and placozoans interact in vitro, and in situ hybridization revealed co-expression in dissociated neurons from the cnidarian Nematostella vectensis. Unexpectedly, the Mint orthologue from the ctenophore Hormiphora californiensis strongly bound the divergent C-terminal ligands of cnidarian and placozoan Ca 2 channels, despite neither the ctenophore Mint, nor the placozoan and cnidarian orthologues, binding the ctenophore Ca 2 channel C-terminus. Altogether, our analyses suggest that the capacity of Mint to bind Ca 2 channels predates bilaterian animals, and that evolutionary changes in Ca 2 channel C-terminal sequences resulted in altered binding modalities with Mint.

PDZ domain mediated interactions with voltage-gated calcium (Ca V ) channel C-termini play important roles in localizing membrane Ca 2+ signaling. The first such interaction was described between the scaffolding protein Mint-1 and Ca V 2.2 in mammals. In this study, we show through various in silico analyses that Mint is an animal-specific gene with a highly divergent N-terminus but a strongly conserved C-terminus comprised of a phosphotyrosine binding domain, two tandem PDZ domains (PDZ-1 and PDZ-2), and a C-terminal auto-inhibitory element that binds and inhibits PDZ-1. In addition to Ca V 2 channels, most genes that interact with Mint are also deeply conserved including amyloid precursor proteins, presenilins, neurexin, and CASK and Veli which form a tripartite complex with Mint in bilaterians. Through yeast and bacterial 2-hybrid experiments, we show that Mint and Ca V 2 channels from cnidarians and placozoans interact in vitro , and in situ hybridization revealed co-expression in dissociated neurons from the cnidarian Nematostella vectensis . Unexpectedly, the Mint orthologue from the ctenophore Hormiphora californiensis strongly binds the divergent C-terminal ligands of cnidarian and placozoan Ca V 2 channels, despite neither the ctenophore Mint, nor the placozoan and cnidarian orthologues, binding the ctenophore Ca V 2 channel C-terminus. Altogether, our analyses suggest that the capacity of Mint to bind CaV2 channels predates pre-bilaterian animals, and that evolutionary changes in Ca V 2 channel C-terminal sequences resulted in altered binding modalities with Mint.PDZ domain mediated interactions with voltage-gated calcium (Ca V ) channel C-termini play important roles in localizing membrane Ca 2+ signaling. The first such interaction was described between the scaffolding protein Mint-1 and Ca V 2.2 in mammals. In this study, we show through various in silico analyses that Mint is an animal-specific gene with a highly divergent N-terminus but a strongly conserved C-terminus comprised of a phosphotyrosine binding domain, two tandem PDZ domains (PDZ-1 and PDZ-2), and a C-terminal auto-inhibitory element that binds and inhibits PDZ-1. In addition to Ca V 2 channels, most genes that interact with Mint are also deeply conserved including amyloid precursor proteins, presenilins, neurexin, and CASK and Veli which form a tripartite complex with Mint in bilaterians. Through yeast and bacterial 2-hybrid experiments, we show that Mint and Ca V 2 channels from cnidarians and placozoans interact in vitro , and in situ hybridization revealed co-expression in dissociated neurons from the cnidarian Nematostella vectensis . Unexpectedly, the Mint orthologue from the ctenophore Hormiphora californiensis strongly binds the divergent C-terminal ligands of cnidarian and placozoan Ca V 2 channels, despite neither the ctenophore Mint, nor the placozoan and cnidarian orthologues, binding the ctenophore Ca V 2 channel C-terminus. Altogether, our analyses suggest that the capacity of Mint to bind CaV2 channels predates pre-bilaterian animals, and that evolutionary changes in Ca V 2 channel C-terminal sequences resulted in altered binding modalities with Mint.

The sodium leak channel NALCN, a key regulator of neuronal excitability, associates with three ancillary subunits that are critical for its function: an extracellular subunit called FAM155, and two cytoplasmic subunits called UNC79 and UNC80. Interestingly, NALCN and FAM155 have orthologous phylogenetic relationships with the fungal calcium channel Cch1 and its extracellular subunit Mid1, however, UNC79 and UNC80 have not been reported outside of animals. In this study, we leveraged expanded gene sequence data available for eukaryotes to re-examine the evolutionary origins of NALCN and Cch1 channel subunits. Our analysis corroborates the direct phylogenetic relationship between NALCN and Cch1 and identifies a larger clade of related channels in additional eukaryotic taxa. We also identify homologues of FAM155/Mid1 in Cryptista algae, and UNC79 and UNC80 homologues in numerous non-metazoan eukaryotes including basidiomycete and mucoromycete fungi, and the microbial eukaryotic taxa Apusomonadida, Malawimonadida, and Discoba. Furthermore, we find that most major animal lineages, except ctenophores, possess a full complement of NALCN subunits. Comparing structural predictions with the solved structure of the human NALCN complex supports orthologous relationships between metazoan and non-metazoan FAM155/Mid1, UNC79, and UNC80 homologues. Together, our analyses reveal unexpected diversity and ancient eukaryotic origins of NALCN/Cch1 channelosome subunits and raise interesting questions about the functional nature of this conserved channel complex within a broad, eukaryotic context.

PDZ domain mediated interactions with voltage-gated calcium (Ca ) channel C-termini play important roles in localizing and compartmentalizing membrane Ca signaling. The first such interaction discovered was between the neuronal multi-domain protein Mint-1, and the presynaptc calcium channel Ca 2.2 in mammals. Although the physiological significance of this interaction is unclear, its occurrence in vertebrates and bilaterian invertebrates suggests important and conserved functions. In this study, we explore the evolutionary origins of Mint and its interaction with Ca 2 channels. Phylogenetic and structural in silico analyses revealed that Mint is an animal-specific gene, like Ca 2 channels, which bears a highly divergent N-terminus but strongly conserved C-terminus comprised of a phosphotyrosine binding domain, two tandem PDZ domains (PDZ-1 and PDZ-2), and a C-terminal auto-inhibitory element that binds and inhibits PDZ-1. Also deeply conserved are other Mint interacting proteins, namely amyloid precursor and related proteins, presenilins, neurexin, as well as CASK and Veli which form a tripartite complex with Mint in bilaterians. Through yeast 2-hybrid and bacterial 2-hybrid experiments, we show that Mint and Ca 2 channels from cnidarians and placozoans interact , and hybridization revealed co-expression of corresponding transcripts in dissociated neurons from the cnidarian . Unexpectedly, the Mint orthologue from the ctenophore was able to strongly bind the divergent C-terminal ligands of cnidarian and placozoan Ca 2 channels, despite neither the ctenophore Mint, nor the placozoan and cnidarian orthologues, binding the ctenophore Ca 2 channel C-terminus. Altogether, our analyses provide a model for the emergence of this interaction in early animals first via adoption of a PDZ ligand by Ca 2 channels, followed by sequence changes in the ligand that caused a modality switch for binding to Mint.

PDZ domain mediated interactions with voltage-gated calcium (CaV) channel C-termini play important roles in localizing membrane Ca2+ signaling. The first such interaction was described between the scaffolding protein Mint-1 and CaV2.2 in mammals. In this study, we show through various in silico analyses that Mint is an animal-specific gene with a highly divergent N-terminus but a strongly conserved C-terminus comprised of a phosphotyrosine binding domain, two tandem PDZ domains (PDZ-1 and PDZ-2), and a C-terminal auto-inhibitory element that binds and inhibits PDZ-1. In addition to CaV2 channels, most genes that interact with Mint are also deeply conserved including amyloid precursor proteins, presenilins, neurexin, and CASK and Veli which form a tripartite complex with Mint in bilaterians. Through yeast and bacterial 2-hybrid experiments, we show that Mint and CaV2 channels from cnidarians and placozoans interact in vitro, and in situ hybridization revealed co-expression in dissociated neurons from the cnidarian Nematostella vectensis. Unexpectedly, the Mint orthologue from the ctenophore Hormiphora californiensis strongly binds the divergent C-terminal ligands of cnidarian and placozoan CaV2 channels, despite neither the ctenophore Mint, nor the placozoan and cnidarian orthologues, binding the ctenophore CaV2 channel C-terminus. Altogether, our analyses suggest that the capacity of Mint to bind CaV2 channels predates pre-bilaterian animals, and that evolutionary changes in CaV2 channel C-terminal sequences resulted in altered binding modalities with Mint.

PDZ domain mediated interactions with voltage-gated calcium (CaV) channel C-termini play important roles in localizing and compartmentalizing membrane Ca2+ signaling. The first such interaction discovered was between the neuronal multi-domain protein Mint-1, and the presynaptc calcium channel CaV2.2 in mammals. Although the physiological significance of this interaction is unclear, its occurrence in vertebrates and bilaterian invertebrates suggests important and conserved functions. In this study, we explore the evolutionary origins of Mint and its interaction with CaV2 channels. Phylogenetic and structural in silico analyses revealed that Mint is an animal-specific gene, like CaV2 channels, which bears a highly divergent N-terminus but strongly conserved C-terminus comprised of a phosphotyrosine binding domain, two tandem PDZ domains (PDZ-1 and PDZ-2), and a C-terminal auto-inhibitory element that binds and inhibits PDZ-1. Also deeply conserved are other Mint interacting proteins, namely amyloid precursor and related proteins, presenilins, neurexin, as well as CASK and Veli which form a tripartite complex with Mint in bilaterians. Through yeast 2-hybrid and bacterial 2-hybrid experiments, we show that Mint and CaV2 channels from cnidarians and placozoans interact in vitro, and in situ hybridization revealed co-expression of corresponding transcripts in dissociated neurons from the cnidarian Nematostella vectensis. Unexpectedly, the Mint orthologue from the ctenophore Hormiphora californiensis was able to strongly bind the divergent C-terminal ligands of cnidarian and placozoan CaV2 channels, despite neither the ctenophore Mint, nor the placozoan and cnidarian orthologues, binding the ctenophore CaV2 channel C-terminus. Altogether, our analyses provide a model for the emergence of this interaction in early animals first via adoption of a PDZ ligand by CaV2 channels, followed by sequence changes in the ligand that caused a modality switch for binding to Mint.Competing Interest StatementThe authors have declared no competing interest.

Clinical examination for compartment syndrome demonstrates lacklustre diagnostic performance characteristics leading many to use compartment pressure measurement as a diagnostic adjunct. Multiple commercial devices are available to measure compartment pressures, but widespread access to these devices remains limited. We report a novel technique to measure compartment pressures using widely available equipment. A 29-year-old male attended our emergency department with a swollen, tense forearm in the setting of life-threatening hyperkalaemia secondary to severe rhabdomyolysis with associated haemodynamic instability. The patient had been lying on his left forearm overnight, giving rise to concerns for acute compartment syndrome. Resuscitation was commended and the hyperkalaemia treated. Staff were unable to locate a dedicated commercial device to obtain compartment pressures. As an alternative, an eighteen-gauge needle was connected to an arterial line pressure transducer, flushed, and zeroed at the level of the patient’s forearm. The needle was sequentially introduced into the dorsal and volar compartments of the forearm and left in a stationary position until a stable reading was recorded. Delta pressures were 0 mmHg and 21 mmHg in the dorsal and volar compartments, respectively, confirming the diagnosis of compartment syndrome. The use of this novel technique was critical to the rapid identification of compartment syndrome in this case. This technique offers many benefits compared to other methods including simplicity, ubiquity of required components, ease of repeatability, and a rapid result. Despite these benefits, awareness of this technique remains low among physicians. We would hope that this case report will improve awareness of this technique.