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Titolo:
ACTIN-TITIN INTERACTION IN CARDIAC MYOFIBRILS - PROBING A PHYSIOLOGICAL-ROLE
Autore:
LINKE WA; IVEMEYER M; LABEIT S; HINSSEN H; RUEGG JC; GAUTEL M;
Indirizzi:
UNIV HEIDELBERG,INST PHYSIOL 2,NEUENHEIMER FELD 326 D-69120 HEIDELBERG GERMANY EUROPEAN MOL BIOL LAB D-69012 HEIDELBERG GERMANY UNIV BIELEFELD,BIOCHEM CELL BIOL GRP D-33501 BIELEFELD GERMANY
Titolo Testata:
Biophysical journal
fascicolo: 2, volume: 73, anno: 1997,
pagine: 905 - 919
SICI:
0006-3495(1997)73:2<905:AIICM->2.0.ZU;2-Q
Fonte:
ISI
Lingua:
ENG
Soggetto:
SKELETAL-MUSCLE; ELASTIC FILAMENTS; Z-LINE; IMMUNOELECTRON MICROSCOPY; MONOCLONAL-ANTIBODIES; VERTEBRATE SKELETAL; SELECTIVE REMOVAL; FORCE GENERATION; SARCOMERE MATRIX; PASSIVE TENSION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
64
Recensione:
Indirizzi per estratti:
Citazione:
W.A. Linke et al., "ACTIN-TITIN INTERACTION IN CARDIAC MYOFIBRILS - PROBING A PHYSIOLOGICAL-ROLE", Biophysical journal, 73(2), 1997, pp. 905-919

Abstract

The high stiffness of relaxed cardiac myofibrils is explainable mainly by the expression of a short-length titin (connectin), the giant elastic protein of the vertebrate myofibrillar cytoskeleton. However, additional molecular features could account for this high stiffness, suchas interaction between titin and actin, which has previously been reported in vitro. To probe this finding for a possible physiological significance, isolated myofibrils from rat heart were subjected to selective removal of actin filaments by a calcium-independent gelsolin fragment, and the ''passive'' stiffness of the specimens was recorded. Uponactin extraction, stiffness decreased by nearly 60%, and to a similardegree after high-salt extraction of thick filaments. Thus actin-titin association indeed contributes to the stiffness of resting cardiac muscle. To identify possible sites of association, we employed a combination of different techniques. Immunofluorescence microscopy revealed that actin extraction increased the extensibility of the previously stiff Z-disc-flanking titin region. Actin-titin interaction within this region was confirmed in in vitro cosedimentation assays, in which multimodule recombinant titin fragments were tested for their ability to interact with F-actin. By contrast, such assays showed no actin-titin-binding propensity for sarcomeric regions outside the Z-disc comb. Accordingly, the results of mechanical measurements demonstrated that competition with native titin by recombinant titin fragments from Z-disc-remote, I-band or A-band regions did not affect passive myofibril stiffness. These results indicate that it is actin-titin association near the Z-disc, but not along the remainder of the sarcomere, that helps toanchor the titin molecule at its N-terminus and maintain a high stiffness of the relaxed cardiac myofibril.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 04/12/20 alle ore 21:55:36