Transglutaminases form a large family of intracellular and extracellular enzymes that catalyse the Ca 2+ -dependent post-translational modification of proteins. Despite significant advances in our understanding of the biolo-gical role of most mammalian transglutaminase isoforms, recent findings suggest new scenarios, most notably for the ubiquitous tissue transglutami-nase. It is becoming apparent that some transglutaminases, normally expressed at low levels in many tissue types, are activated and⁄or over-expressed in a variety of diseases, thereby resulting in enhanced concentra-tions of cross-linked proteins. .
