Electrophysiological activity of the C‐peptide of the Locusta insulin‐related peptide Effect on the membrane conductance of Locusta neurones in vitro

FEBS Letters

Luu, Bang²  Beadle, David J.¹  Trifilieff, Elisabeth²  Bermudez, Isabel¹  Hietter, Helene² 

[1] School of Biological and Molecular Sciences, Oxford Polytechnic, Headington, Oxford, OX3 OBP, England;Laboratoire de Chimie Organique des Substances Naturelles, Associe au CNRS, 5 Rue Blaise Pascal, F-67084 Strasbourg, France

关键词: Neuropeptide;    Ionic current;    Insulin peptide: C-Peptide;    Boc;    N-tert-butyloxycarbonyl;    BOP;    benzotriazoyl-N-oxy-tris(dimethylamino)phosphonium hexafluorophosphate;    DCM;    dichloromethane;    DMF;    dimethylformamide;    DIEA;    N-ethyl-diisopropylamin;    HF;    hydrogen fluoride;    NMP;    1-methyl-2-pyrrolidone;    TFA;    trifluoroacetic acid;    CNS;    central nervous system;    Cs;    cesium;    Rb;    rubidium;   

DOI  :  10.1016/0014-5793(91)81170-D

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The C-peptide of Locusta insulin-related peptide, which is a 50 residue peptide originally isolated from the corpora cardiaca of the insect Locusta migratoria and to which we refer as 5-kDa peptide, has been synthesised chemically by the solid-phase metho, using a BOC strategy. Since this peptide contains in its sequence a potential monobasic cleavage site, we also synthesised its 1–38 residue-related fragment, named 4-kDa peptide, although we have no hints of its natural occurrence in the corpora cardiaca. Electrophysiological studies have shown that both the 5-kDa and 4-kDa peptides depolarise the membrane and increase the membrane conductance of neurones freshly isolated from the thoracic ganglia of Locusta. Under voltage-clamp conditions, the current underlying these effects was inwardly directed and could be resolved into 2 components. One component, I(5-kDa)₁, activated at potentials more hyperpolarised than −50 mV, peaked at about −75 mV and was blocked by the potassium channel blockers cesium and rubidium. The second component, I(5-kDa)₂ was activated at potentials more depolarised than −50 mV, increased with depolarisation and was not blocked by cesium and rubidium. The effects of the 5-kDa and 4-kDa peptides on the membrane potential and membrane conductance of Locusta neurones suggest that these peptides may have a physiological role in the central nervous system of insects.

【 授权许可】

Unknown