Membrane-anchored cyclin A2 triggers Cdc2 activation in Xenopus oocyte

In Xenopus oocyte, the formation of complexes between neosynthesized cyclin s and Cdc2 contributes to Cdc2 kinase activation that triggers meiotic divi sions. It has been proposed that cytoplasmic membranes could be involved in this process. To investigate this possibility, we have injected in the ooc yte two undegradable human cyclin A2 mutants anchored to the endoplasmic re ticulum (ER) membrane. They encode fusion proteins between the truncated cy clin A2-Delta 152 and a viral or cellular ER-targeting domain. We show that both mutants are fully functional as mitotic cyclins when expressed in Xen opus oocytes, bind Cdc2 and activate M-phase promoting factor. (C) 2001 Pub lished by Elsevier Science B.V. on behalf of the Federation of European Bio chemical Societies.