Functional implications of modifying RyR-activating peptides for membrane permeability

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Title Functional implications of modifying RyR-activating peptides for membrane permeability
Author Dulhunty, Angela F.; Cengia, Louise; Young, Jacqui; Pace, Suzy M.; Harvey, Peta J.; Lamb, Graham D.; Chan, Yiu-Ngok; Wimmer, Norbert; Toth, Istvan; Casarotto, Marco G.
Journal Name British Journal of Pharmacology
Year Published 2005
Place of publication United Kingdom
Publisher John Wiley & Sons Ltd.
Abstract Our aim was to determine whether lipoamino acid conjugation of peptides that are high-affinity activators of ryanodine receptor (RyR) channels would (a) render the peptides membrane permeable, (b) alter their structure or (a) reduce their activity. The peptides correspond to the A region of the II-III loop of the skeletal dihydropyridine receptor. 2. The lipoamino acid conjugation increased the apparent permeability of the peptide across the Caco-2 cell monolayer by up to approximately 20-fold. 3. Nuclear magnetic resonance showed that the alpha-helical structure of critical basic residues, required for optimal activation of RyRs, was retained after conjugation. 4. The conjugated peptides were more effective in enhancing resting Ca2+ release, Ca2+-induced Ca2+ release and caffeine-induced Ca2+ release from isolated sarcoplasmic reticulum (SR) than their unconjugated counterparts, and significantly enhanced caffeine-induced Ca2+ release from mechanically skinned extensor digitorum longus (EDL) fibres. 5. The effect of both conjugated and unconjugated peptides on Ca2+ release from skeletal SR was 30-fold greater than their effect on either cardiac Ca2+ release or on the Ca2+ Mg2+ ATPase. 6. A small and very low affinity effect of the peptide in slowing Ca2+ uptake by the Ca2+, Mg2+ ATPase was exacerbated by lipoamino acid conjugation in both isolated SR and in skinned EDL fibres. 7. The results show that lipoamino acid conjugation of A region peptides increases their membrane permeability without impairing their structure or efficacy in activating skeletal and cardiac RyRs.
Peer Reviewed Yes
Published Yes
Alternative URI
Volume 144
Issue Number 6
Page from 743
Page to 754
ISSN 0007-1188
Date Accessioned 2006-07-22
Language en_AU
Faculty Griffith Health Faculty
Subject PRE2009-Basic Pharmacology; PRE2009-Pharmaceutical Sciences and Pharmacy
Publication Type Journal Articles (Refereed Article)
Publication Type Code c1x

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