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The structure of the Staphylococcus aureus alpha-hemolysin pore has been determined to 1.9 A resolution. Contained within the mushroom-shaped homo-oligomeric heptamer is a solvent-filled channel, 100 A in length, that runs along the sevenfold axis and ranges from 14 A to 46 A in diameter. The lytic, transmembrane domain comprises the lower half of a(More)
The detection of organic molecules is important in many areas, including medicine, environmental monitoring and defence. Stochastic sensing is an approach that relies on the observation of individual binding events between analyte molecules and a single receptor. Engineered transmembrane protein pores are promising sensor elements for stochastic detection,(More)
Binding of cAMP by the five neuronal isoforms (N1-5) of the regulatory (R) subunit of the Aplysia cAMP-dependent protein kinase is diminished in sensory neurons stimulated to produce long-term presynaptic facilitation. To determine how the cAMP-binding activity of the R subunits is lost, we isolated cDNAs encoding N4, which is a homolog of mammalian RI.(More)
Extended retro (reversed) peptide sequences have not previously been accommodated within functional proteins. Here, we show that the entire transmembrane portion of the beta-barrel of the pore-forming protein alpha-hemolysin can be formed by retrosequences comprising a total of 175 amino acid residues, 25 contributed by the central sequence of each subunit(More)
abstract Noncovalent molecular adapters, such as cyclodextrins, act as binding sites for channel blockers when lodged in the lumen of the ␣-hemolysin (␣ HL) pore, thereby offering a basis for the detection of a variety of organic molecules with ␣ HL as a sensor element. ␤-Cyclodextrin (␤ CD) resides in the wild-type ␣ HL pore for several hundred(More)
We describe biosensor elements that are capable of identifying individual DNA strands with single-base resolution. Each biosensor element consists of an individual DNA oligonucleotide covalently attached within the lumen of the alpha-hemolysin (alphaHL) pore to form a "DNA-nanopore". The binding of single-stranded DNA (ssDNA) molecules to the tethered DNA(More)
Somatostatin-14 (SST) inhibits insulin and glucagon secretion by activating G protein-coupled somatostatin receptors (SSTRs), of which five isoforms exist (SSTR1-5). In mice, the effects on pancreatic β-cells are mediated by SSTR5, whereas α-cells express SSTR2. In both cell types, SSTR activation results in membrane hyperpolarization and suppression of(More)
Two type II regulatory (R) subunits of cAMP-dependent protein kinase (PKA) of 50 and 47 kDa have been identified in Aplysia neurons by several criteria which include phosphorylation by the catalytic subunit of PKA and nanomolar affinity for a peptide fragment of the human thyroid protein Ht 31, properties that in mammals distinguish type II from type I R(More)
Styryl dyes are widely used to study synaptic vesicle (SV) recycling in neurons; vesicles are loaded with dye during endocytosis, and dye is subsequently released via exocytosis. During putative kiss-and-run exocytosis, efflux of dye from individual SVs has been proposed to occur via two sequential steps: dissociation from the membrane followed by(More)