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Identification of high molecular weight forms of inositol 1,4,5-trisphosphate 3-kinase in rat thymus and human lymphocytes

par D'Santos, C. S.;Communi, David ;Ludgate, Marian;Vanweyenberg, Valérie ;Takazawa, Kazunaga;Erneux, Christophe
Référence Cellular Signalling, 6, 3, page (335-344)
Publication Publié, 1994

Article révisé par les pairs

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Résumé :

A soluble inositol 1,4,5-trisphosphate 3-kinase (InsP3 3-kinase) has been characterized from extracts of rat thymus. The enzyme was shown to have a molecular weight within the range 98,000-114,000 M(r) as determined by regeneration of enzyme activity from sodium dodecyl sulphate polyacrylamide gels. The enzyme phosphorylates inositol 1,4,5-trisphosphate (InsP3) to inositol 1,3,4,5-tetrakisphosphate (InsP4) with an apparent Km of 3.1 +/- 0.4 microM. The enzyme is stimulated 4-6-fold by Ca2+/calmodulin and is not recognised by polyclonal antisera raised against rat brain InsP3 3-kinase A. High levels of InsP3 3-kinase activity were also detected in soluble extracts of human lymphocyte preparations. The human lymphocyte enzyme was shown to have a molecular weight between 61,000 and 70,000 M(r) as judged by SDS-PAGE, and was stimulated approximately 10-fold in the presence of Ca2+/calmodulin. These results establish that InsP3 3-kinase from rat thymus and human lymphocyte preparations represent high molecular weight isoenzymes of the InsP3 3-kinase family.