A number of molecular defects with the potential to cause sudden cardiac death are known, but all have been in proteins directly linked to ion transport processes. Now, a study of members of a French family with an inherited condition, type 4 long-QT cardiac arrhythmia, has uncovered a different basis for life-threatening cardiac disease (Nature, Vol. 421, No. 6923, pp. 634-639, 6 FEBRUARY 2003).
The mutation lies in the structural protein ankyrin-B, previously linked to membrane defects in a type of anaemia, report Vann Bennett of Duke University Medical Center, Durham, North Carolina, and colleagues in this week’s Nature. They explain that ankyrin-B commonly anchors membrane proteins in cells. Its involvement in cardiac signalling suggests that correct positioning of ion transporters by structural proteins is crucially important for their function.
"Although this study deals with a primarily cardiac disease, the ubiquitous distribution of ankyrin-B and related proteins raises the possibility that other tissues and organs are affected in this and similar genetic syndromes," says Stanley Nattel of the Montreal Heart Institute and University of Montreal, Quebec, Canada in an accompanying News and Views article.
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