The complete gene sequence of titin, expression of an unusual approximately 700-kDa titin isoform, and its interaction with obscurin identify a novel Z-line to I-band linking system.
Circ Res
; 89(11): 1065-72, 2001 Nov 23.
Article
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| MEDLINE
| ID: mdl-11717165
Titin is a giant vertebrate striated muscle protein with critical importance for myofibril elasticity and structural integrity. We show here that the complete sequence of the human titin gene contains 363 exons, which together code for 38 138 residues (4200 kDa). In its central I-band region, 47 novel PEVK exons were found, which contribute to titin's extensible spring properties. Additionally, 3 unique I-band titin exons were identified (named novex-1 to -3). Novex-3 functions as an alternative titin C-terminus. The novex-3 titin isoform is approximately 700 kDa in size and spans from Z1-Z2 (titin's N-terminus) to novex-3 (C-terminal exon). Novex-3 titin specifically interacts with obscurin, a 721-kDa myofibrillar protein composed of 57 Ig/FN3 domains, followed by one IQ, SH3, DH, and a PH domain at its C-terminus. The obscurin domains Ig48/Ig49 bind to novex-3 titin and target to the Z-line region when expressed as a GFP fusion protein in live cardiac myocytes. Immunoelectron microscopy detected the C-terminal Ig48/Ig49 obscurin epitope near the Z-line edge. The distance from the Z-line varied with sarcomere length, suggesting that the novex-3 titin/obscurin complex forms an elastic Z-disc to I-band linking system. This system could link together calcium-dependent, SH3-, and GTPase-regulated signaling pathways in close proximity to the Z-disc, a structure increasingly implicated in the restructuring of sarcomeres during cardiomyopathies.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Proteínas Quinasas
/
Sarcómeros
/
Factores de Intercambio de Guanina Nucleótido
/
Proteínas Musculares
/
Miocardio
Tipo de estudio:
Prognostic_studies
Límite:
Animals
/
Humans
Idioma:
En
Revista:
Circ Res
Año:
2001
Tipo del documento:
Article
País de afiliación:
Alemania
Pais de publicación:
Estados Unidos