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Tissue expression and actin binding of a novel N-terminal utrophin isoform


Zuellig, R A; Bornhauser, B C; Amstutz, R; Constantin, B; Schaub, M C (2011). Tissue expression and actin binding of a novel N-terminal utrophin isoform. Journal of Biomedicine and Biotechnology, 2011:904547.

Abstract

Utrophin and dystrophin present two large proteins that link the intracellular actin cytoskeleton to the extracellular matrix via the C-terminal-associated protein complex. Here we describe a novel short N-terminal isoform of utrophin and its protein product in various rat tissues (N-utro, 62 kDa, amino acids 1-539, comprising the actin-binding domain plus the first two spectrin repeats). Using different N-terminal recombinant utrophin fragments, we show that actin binding exhibits pronounced negative cooperativity (affinity constants K(1) = ∼5 × 10(6) and K(2) = ∼1 × 10(5 )M(-1)) and is Ca(2+)-insensitive. Expression of the different fragments in COS7 cells and in myotubes indicates that the actin-binding domain alone binds exlusively to actin filaments. The recombinant N-utro analogue binds in vitro to actin and in the cells associates to the membranes. The results indicate that N-utro may be responsible for the anchoring of the cortical actin cytoskeleton to the membranes in muscle and other tissues.

Abstract

Utrophin and dystrophin present two large proteins that link the intracellular actin cytoskeleton to the extracellular matrix via the C-terminal-associated protein complex. Here we describe a novel short N-terminal isoform of utrophin and its protein product in various rat tissues (N-utro, 62 kDa, amino acids 1-539, comprising the actin-binding domain plus the first two spectrin repeats). Using different N-terminal recombinant utrophin fragments, we show that actin binding exhibits pronounced negative cooperativity (affinity constants K(1) = ∼5 × 10(6) and K(2) = ∼1 × 10(5 )M(-1)) and is Ca(2+)-insensitive. Expression of the different fragments in COS7 cells and in myotubes indicates that the actin-binding domain alone binds exlusively to actin filaments. The recombinant N-utro analogue binds in vitro to actin and in the cells associates to the membranes. The results indicate that N-utro may be responsible for the anchoring of the cortical actin cytoskeleton to the membranes in muscle and other tissues.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Institute of Pharmacology and Toxicology
07 Faculty of Science > Institute of Pharmacology and Toxicology

04 Faculty of Medicine > University Hospital Zurich > Clinic for Endocrinology and Diabetology
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:2011
Deposited On:21 Jan 2012 10:45
Last Modified:07 Dec 2017 11:35
Publisher:Hindawi Publishing Corporation
ISSN:1110-7243
Free access at:PubMed ID. An embargo period may apply.
Publisher DOI:https://doi.org/10.1155/2011/904547
PubMed ID:22228988

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