Bennett, P.M. and Maggs, A.M. and Baines, A.J. and Pinder, J.C. (2006) The transitional junction: a new functional subcellular domain at the intercalated disc. Molecular Biology of the Cell, 17 . pp. 2091-2100.
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We define here a previously unrecognized structural element close to the heart muscle plasma membrane at the intercalated disc where the myofibrils lead into the adherens junction. At this location, the plasma membrane is extensively folded. Immunofluorescence and immunogold electron microscopy reveal a spectrin-rich domain at the apex of the folds. These domains occur at the axial level of what would be the final Z-disc of the terminal sarcomere in the myofibril, although there is no Z-disc-like structure there. However, a sharp transitional boundary lies between the myofibrillar I-band and intercalated disc thin filaments, identifiable by the presence of Z-disc proteins, alpha-actinin, and N-terminal titin. This allows for the usual elastic positioning of the A-band in the final sarcomere, whereas the transduction of the contractile force normally associated with the Z-disc is transferred to the adherens junctions at the plasma membrane. The axial conjunction of the transitional junction with the spectrin-rich domains suggests a mechanism for direct communication between intercalated disc and contractile apparatus. In particular, it provides a means for sarcomeres to be added to the ends of the cells during growth. This is of particular relevance to understanding myocyte elongation in dilated cardiomyopathy.
|Subjects:||Q Science > Q Science (General)|
|Divisions:||Faculties > Science Technology and Medical Studies > School of Biosciences > Cell & Developmental Biology Group|
|Depositing User:||Sue Davies|
|Date Deposited:||19 Dec 2007 17:44|
|Last Modified:||05 Sep 2011 23:19|
|Resource URI:||http://kar.kent.ac.uk/id/eprint/15 (The current URI for this page, for reference purposes)|
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