Erik Karlsson

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There are five subtypes of muscarinic acetylcholine receptors (M(1) to M(5)) which control a large number of physiological processes, such as the function of heart and smooth muscles, glandular secretion, release of neurotransmitters, gene expression and cognitive functions as learning and memory. A selective ligand is very useful for studying the function(More)
MT-7 (1 - 30 nM), a peptide toxin isolated from the venom of the green mamba Dendroaspis angusticeps and previously found to bind selectively to the muscarinic M(1) receptor, inhibited the acetylcholine (ACh)-stimulated [(35)S]-guanosine-5'-O-(3-thio)triphosphate ([(35)S]-GTPgammaS) binding to membranes of Chinese hamster ovary (CHO) cells stably expressing(More)
The muscarinic acetylcholine receptors are monomeric proteins with seven hydrophobic, membrane spanning helices, and share a common evolutionary origin with the other members of the superfamily of membrane proteins known as seven-helix receptors. The amino acid sequences of five different muscarinic acetylcholine receptors, called m1, m2, m3, m4 and m5 have(More)
A peptide toxin, ShK, that blocks voltage-dependent potassium channels was isolated from the whole body extract of the Caribbean sea anemone Stichodactyla helianthus. It competes with dendrotoxin I and alpha-dendrotoxin for binding to synaptosomal membranes of rat brain, facilities acetylcholine release at an avian neuromuscular junction and suppresses K+(More)
Muscarinic toxin 3 (MT3) (65 amino acids, four disulphides, M(r) 7379) was isolated from the venom of the African snake Dendroaspis angusticeps (green mamba) and its amino acid sequence determined. Its ability to inhibit the binding of [3H]N-methylscopolamine ([3H]NMS) to Chinese hamster ovary cells stably expressing subtypes of muscarinic receptors was(More)
Two protein toxins that displace the muscarinic antagonist quinuclidinyl benzilate from rat cortex synaptosomal membranes have been isolated from the green mamba (Dendroaspis angusticeps) venom by gel filtration on sephadex G-50, chromatography on the ion-exchangers Bio-Rex 70 and Sulphopropyl-Sephadex C-25 and reversed-phase HPLC. Toxin 1 has 64 amino(More)
The venom of the green mamba, Dendroaspis angusticeps has previously been shown to produce neuromuscular facilitation by increasing acetylcholine release. After gel filtration and ion-exchange chromatography of the whole venom, a basic polypeptide with facilitatory actions was isolated. This polypeptide, named dendrotoxin, has 59 amino acid residues,(More)
1 Five polypeptides, which were isolated from elapid snake venoms and which are structurally related to protease inhibitors, were tested for action on isolated biventer cervicis nerve-muscle preparations of the chick. 2 Dendrotoxin from the Eastern green mamba (Dendroaspis angusticeps) and toxins K and I from the black mamba (Dendroaspis polylepis(More)
An aqueous extract from the unripe fruits of the tropical plant Momordica charantia was found to be a potent stimulator of insulin release from beta-cell-rich pancreatic islets isolated from obese-hyperglycemic mice. The stimulation of insulin release was partially reversible. It differed from that of D-glucose and other commonly employed insulin(More)
The potassium channel toxin secreted by the sea anemone Bunodosoma granulifera (BgK) is a 37-amino-acid peptide containing three disulfide bridges. Because a synthetic peptide corresponding to the reported sequence of BgK was found not to fold properly, the sequence was determined again. The new sequence differed from the previous one in the C-terminal(More)