Nature and origin of gap filaments in striated muscle

K. Trombitás, P. H W W Baatsen, M. Kellermayer, G. H. Pollack

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

Immunoelectron microscopy was used to study the nature and origin of 'gap' filaments in frog semitendinosus muscle. Gap filaments are fine longitudinal filaments observable only in sarcomeres stretched beyond thick/thin filament overlap: they occupy the gap between the tips of thick and thin filaments. To test whether the gap filaments are part of the titin-filament system, we employed monoclonal antibodies to titin (T-11, Sigma) and observed the location of the epitope at a series of sarcomere lengths. At resting sarcomere length, the epitope was positioned in the I-band approximately 50 nm beyond the apparent ends of the thick filament. The location did not change perceptibly with increasing sarcomere length up to 3.6 μm. Above 3.6 μm, the span between the epitope and the end of the A-band abruptly increased, and above 4 μm, the antibodies could be seen to decorate the gap filaments. Between 5 and 6 μm, the epitope remained approximately in the middle of the gap. Even with this high degree of stretch, the label remained more or less aligned across the myofibril. The abrupt increase of span beyond 3.6 μm implies that the A-band domain of titin is pulled free of its anchor points along the thick filament, and moves toward the gap. Although this domain is functionally inextensible at physiological sarcomere length, the epitope movement in extremely stretched muscle shows that it is intrinsically elastic. Thus, the evidence confirms that gap filaments are clearly part of the titin-filament system. They are derived not only from the I-band domain of titin, but also from its A-band domain.

Original languageEnglish
Pages (from-to)809-814
Number of pages6
JournalJournal of Cell Science
Volume100
Issue number4
Publication statusPublished - Dec 1991

Fingerprint

Connectin
Sarcomeres
Striated Muscle
Epitopes
Muscles
Immunoelectron Microscopy
Myofibrils
Anura
Monoclonal Antibodies
Antibodies

Keywords

  • Elastic filament
  • Immunoelectron microscopy
  • Skeletal muscle
  • Titin

ASJC Scopus subject areas

  • Cell Biology

Cite this

Trombitás, K., Baatsen, P. H. W. W., Kellermayer, M., & Pollack, G. H. (1991). Nature and origin of gap filaments in striated muscle. Journal of Cell Science, 100(4), 809-814.

Nature and origin of gap filaments in striated muscle. / Trombitás, K.; Baatsen, P. H W W; Kellermayer, M.; Pollack, G. H.

In: Journal of Cell Science, Vol. 100, No. 4, 12.1991, p. 809-814.

Research output: Contribution to journalArticle

Trombitás, K, Baatsen, PHWW, Kellermayer, M & Pollack, GH 1991, 'Nature and origin of gap filaments in striated muscle', Journal of Cell Science, vol. 100, no. 4, pp. 809-814.
Trombitás K, Baatsen PHWW, Kellermayer M, Pollack GH. Nature and origin of gap filaments in striated muscle. Journal of Cell Science. 1991 Dec;100(4):809-814.
Trombitás, K. ; Baatsen, P. H W W ; Kellermayer, M. ; Pollack, G. H. / Nature and origin of gap filaments in striated muscle. In: Journal of Cell Science. 1991 ; Vol. 100, No. 4. pp. 809-814.
@article{6970b768d4d84e66a315b0138c444f0a,
title = "Nature and origin of gap filaments in striated muscle",
abstract = "Immunoelectron microscopy was used to study the nature and origin of 'gap' filaments in frog semitendinosus muscle. Gap filaments are fine longitudinal filaments observable only in sarcomeres stretched beyond thick/thin filament overlap: they occupy the gap between the tips of thick and thin filaments. To test whether the gap filaments are part of the titin-filament system, we employed monoclonal antibodies to titin (T-11, Sigma) and observed the location of the epitope at a series of sarcomere lengths. At resting sarcomere length, the epitope was positioned in the I-band approximately 50 nm beyond the apparent ends of the thick filament. The location did not change perceptibly with increasing sarcomere length up to 3.6 μm. Above 3.6 μm, the span between the epitope and the end of the A-band abruptly increased, and above 4 μm, the antibodies could be seen to decorate the gap filaments. Between 5 and 6 μm, the epitope remained approximately in the middle of the gap. Even with this high degree of stretch, the label remained more or less aligned across the myofibril. The abrupt increase of span beyond 3.6 μm implies that the A-band domain of titin is pulled free of its anchor points along the thick filament, and moves toward the gap. Although this domain is functionally inextensible at physiological sarcomere length, the epitope movement in extremely stretched muscle shows that it is intrinsically elastic. Thus, the evidence confirms that gap filaments are clearly part of the titin-filament system. They are derived not only from the I-band domain of titin, but also from its A-band domain.",
keywords = "Elastic filament, Immunoelectron microscopy, Skeletal muscle, Titin",
author = "K. Trombit{\'a}s and Baatsen, {P. H W W} and M. Kellermayer and Pollack, {G. H.}",
year = "1991",
month = "12",
language = "English",
volume = "100",
pages = "809--814",
journal = "Journal of Cell Science",
issn = "0021-9533",
publisher = "Company of Biologists Ltd",
number = "4",

}

TY - JOUR

T1 - Nature and origin of gap filaments in striated muscle

AU - Trombitás, K.

AU - Baatsen, P. H W W

AU - Kellermayer, M.

AU - Pollack, G. H.

PY - 1991/12

Y1 - 1991/12

N2 - Immunoelectron microscopy was used to study the nature and origin of 'gap' filaments in frog semitendinosus muscle. Gap filaments are fine longitudinal filaments observable only in sarcomeres stretched beyond thick/thin filament overlap: they occupy the gap between the tips of thick and thin filaments. To test whether the gap filaments are part of the titin-filament system, we employed monoclonal antibodies to titin (T-11, Sigma) and observed the location of the epitope at a series of sarcomere lengths. At resting sarcomere length, the epitope was positioned in the I-band approximately 50 nm beyond the apparent ends of the thick filament. The location did not change perceptibly with increasing sarcomere length up to 3.6 μm. Above 3.6 μm, the span between the epitope and the end of the A-band abruptly increased, and above 4 μm, the antibodies could be seen to decorate the gap filaments. Between 5 and 6 μm, the epitope remained approximately in the middle of the gap. Even with this high degree of stretch, the label remained more or less aligned across the myofibril. The abrupt increase of span beyond 3.6 μm implies that the A-band domain of titin is pulled free of its anchor points along the thick filament, and moves toward the gap. Although this domain is functionally inextensible at physiological sarcomere length, the epitope movement in extremely stretched muscle shows that it is intrinsically elastic. Thus, the evidence confirms that gap filaments are clearly part of the titin-filament system. They are derived not only from the I-band domain of titin, but also from its A-band domain.

AB - Immunoelectron microscopy was used to study the nature and origin of 'gap' filaments in frog semitendinosus muscle. Gap filaments are fine longitudinal filaments observable only in sarcomeres stretched beyond thick/thin filament overlap: they occupy the gap between the tips of thick and thin filaments. To test whether the gap filaments are part of the titin-filament system, we employed monoclonal antibodies to titin (T-11, Sigma) and observed the location of the epitope at a series of sarcomere lengths. At resting sarcomere length, the epitope was positioned in the I-band approximately 50 nm beyond the apparent ends of the thick filament. The location did not change perceptibly with increasing sarcomere length up to 3.6 μm. Above 3.6 μm, the span between the epitope and the end of the A-band abruptly increased, and above 4 μm, the antibodies could be seen to decorate the gap filaments. Between 5 and 6 μm, the epitope remained approximately in the middle of the gap. Even with this high degree of stretch, the label remained more or less aligned across the myofibril. The abrupt increase of span beyond 3.6 μm implies that the A-band domain of titin is pulled free of its anchor points along the thick filament, and moves toward the gap. Although this domain is functionally inextensible at physiological sarcomere length, the epitope movement in extremely stretched muscle shows that it is intrinsically elastic. Thus, the evidence confirms that gap filaments are clearly part of the titin-filament system. They are derived not only from the I-band domain of titin, but also from its A-band domain.

KW - Elastic filament

KW - Immunoelectron microscopy

KW - Skeletal muscle

KW - Titin

UR - http://www.scopus.com/inward/record.url?scp=0026344028&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0026344028&partnerID=8YFLogxK

M3 - Article

C2 - 1726102

AN - SCOPUS:0026344028

VL - 100

SP - 809

EP - 814

JO - Journal of Cell Science

JF - Journal of Cell Science

SN - 0021-9533

IS - 4

ER -