The sensitivity of tissue transglutaminase to activation by Ca2+ and other cellular factors was investigated using the enzyme purified from rat liver. The inclusion of Mg2+ in the assay system appeared to reduce the Ca2+-requirement of the enzyme when native N,N′-dimethylcasein was used as the protein acceptor substrate. However, when this protein was dephosphorylated, the Ca2+-requirement was unaffected by Mg2+. In addition, using this modified assay, a Km for Ca2+ was calculated to be in the range of 3–4 μM, at least an order of magnitude lower than that obtained with native acceptor substrate. Membrane phospholipids, 1,2-diolein and calmodufin were found not to affect the activation oftransglutaminase by Ca2+. The sensitivity of transglutaminase to Ca2+ which we have now demonstrated suggests that this enzyme may directly act as a receptor protein for Ca2+ during stimulusresponse coupling mediated by this cation.
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Research Article|
December 01 1985
Activation of transglutaminase at calcium levels consistent with a role for this enzyme as a calcium receptor protein
D. Hand;
D. Hand
1Department of Life Sciences, Trent Polytechnic, Clifton Lane, Nottingham NG11 8NS, UK
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P. J. Bungay;
P. J. Bungay
1Department of Life Sciences, Trent Polytechnic, Clifton Lane, Nottingham NG11 8NS, UK
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B. M. Elliott;
B. M. Elliott
1Central Toxicology Laboratory, Imperial Chemical Industries PLC, Alderley Park, Macclesfield SK10 4TJ, UK
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M. Griffin
M. Griffin
1Department of Life Sciences, Trent Polytechnic, Clifton Lane, Nottingham NG11 8NS, UK
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Publisher: Portland Press Ltd
Received:
October 03 1985
Online ISSN: 1573-4935
Print ISSN: 0144-8463
© 1985 The Biochemical Society
1985
Biosci Rep (1985) 5 (12): 1079–1086.
Article history
Received:
October 03 1985
Citation
D. Hand, P. J. Bungay, B. M. Elliott, M. Griffin; Activation of transglutaminase at calcium levels consistent with a role for this enzyme as a calcium receptor protein. Biosci Rep 1 December 1985; 5 (12): 1079–1086. doi: https://doi.org/10.1007/BF01119629
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