Differential incorporation of biotinylated polyamines by transglutaminase 2

Abstract

Polyamine incorporation or cross-linking of proteins, post-translational modifications mediated by transglutaminase 2 (Tease 2), have been implicated in a variety of physiological functions including cell adhesion, extracellular matrix formation and apoptosis. To better understand the intracellular regulation mechanism of Tease 2, the properties of biotinylated polyamines as substrates for determining in situ Tease activity were analyzed. We synthesized biotinylated spermine (BS), and compared the in vitro and in situ incorporation of BS with that of biotinylated pentylamine (BP), which is an artificial polyamine derivative. When measured in vitro, BP showed a significantly higher incorporation rate than BS. In contrast, in situ incorporation of both BS and BP was not detected even in Tease 2-overexpressed 293 cells. Cells exposed to high calcium showed a marked increase of BP incorporation but not of BS. These data indicate that the in situ activity of Tease 2 gives different results with different substrates, and suggest the possibility of overrepresentation of in situ Tease 2 activity when assayed with BP. Therefore, careful interpretation or evaluation of in situ Tease 2 activity may be required. (C) 2002 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.