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The carboxyl-terminal ahnak domain induces actin bundling and stabilizes muscle contraction

Item Type:Article
Title:The carboxyl-terminal ahnak domain induces actin bundling and stabilizes muscle contraction
Creators Name:Haase, H. and Pagel, I. and Khalina, Y. and Zacharzowsky, U. and Person, V. and Lutsch, G. and Petzhold, D. and Kott, M. and Schaper, J. and Morano, I.
Abstract:Ahnak, a 700 kDa protein, is expressed in a variety of cells and has been implicated in different cell-type-specific functions. In the human heart, we observed an endogenous carboxyl-terminal 72 kDa ahnak fragment that copurified with myofibrillar proteins. Immunocytochemistry combined with confocal microscopy localized this fragment to the intercalated discs and close to the Z-line of cardiomyocytes. No endogenous myofibrillar ahnak fragment was observed in the skeletal muscle. We elucidated the role of the recombinant carboxyl-terminal ahnak fragment (ahnak-C2) in actin filament organization and in the function of muscle fibers. Addition of ahnak-C2 to actin filaments induced filament bundling into paracrystalline-like structures as revealed by electron microscopy. Incubation of demembranated skeletal muscle fibers with ahnak-C2 attenuated the decline in isometric force development upon repeated contraction-relaxation cycles. Our results suggest that the carboxyl-terminal ahnak domain exerts a stabilizing effect on muscle contractility via its interaction with actin of thin filaments.
Keywords:Actins, Amino Acid Sequence, Confocal Microscopy, Electron Microscopy, Indirect Fluorescent Antibody Technique, Membrane Proteins, Molecular Sequence Data, Muscle Contraction, Myocardium, Neoplasm Proteins, Recombinant Fusion Proteins, Skeletal Muscle, Sprague-Dawley Rats, Tertiary Protein Structure, Three-Dimensional Imaging, Animals, Rabbits, Rats
Source:FASEB Journal
Publisher:Federation of American Societies for Experimental Biology
Page Range:839-841
Date:May 2004
Official Publication:https://doi.org/10.1096/fj.03-0446fje
PubMed:View item in PubMed

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