Premium
Electrophysiological activity of the C‐peptide of the Locusta insulin‐related peptide Effect on the membrane conductance of Locusta neurones in vitro
Author(s) -
Bermudez Isabel,
Beadle David J.,
Trifilieff Elisabeth,
Luu Bang,
Hietter Helene
Publication year - 1991
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(91)81170-d
Subject(s) - peptide , membrane potential , depolarization , biology , electrophysiology , biochemistry , membrane , biophysics , chemistry , neuroscience
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.