Invertebrate connectin spans as much as 3.5 μm in the giant sarcomeres of crayfish claw muscle

In crayfish claw closer muscle, the giant sarcomeres are 8.3 μm long at rest, four times longer than vertebrate striated muscle sarcomeres, and they are extensible up to 13 μm upon stretch. Invertebrate connectin (I‐connectin) is an elastic protein which holds the A band at the center of the sarcome...

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Bibliographic Details
Published in:The EMBO journal 2001-09, Vol.20 (17), p.4826-4835
Main Authors: Fukuzawa, Atsushi, Shimamura, Jinen, Takemori, Shigeru, Kanzawa, Nobuyuki, Yamaguchi, Maki, Sun, Peng, Maruyama, Koscak, Kimura, Sumiko
Format: Article
Language:English
Subjects:
Astacura
connectin
D-titin
elasticity
kettin
titin
Online Access:Get full text
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Summary:In crayfish claw closer muscle, the giant sarcomeres are 8.3 μm long at rest, four times longer than vertebrate striated muscle sarcomeres, and they are extensible up to 13 μm upon stretch. Invertebrate connectin (I‐connectin) is an elastic protein which holds the A band at the center of the sarcomere. The entire sequence of crayfish I‐connectin was predicted from cDNA sequences of 53 424 bp (17 352 residues; 1960 kDa). Crayfish I‐connectin contains two novel 68‐ and 71‐residue repeats, and also two PEVK domains and one kettin region. Kettin is a small isoform of I‐connectin. Immunoblot tests using antibody to the 68‐residue repeats revealed the presence of I‐connectin also in long sarcomeres of insect leg muscle and barnacle ventral muscle. Immunofluorescence microscopy demonstrated that the two repeats, the long spacer and the two PEVK domains contribute to sarcomere extension. These regions rich in charged amino acids, occupying 63% of the crayfish I‐connectin molecule, may allow a span of a 3.5 μm distance as a new class of composite spring.
ISSN:0261-4189
1460-2075
DOI:10.1093/emboj/20.17.4826