Isc10, an Inhibitor That Links the Anaphase-Promoting Complex to a Meiosis-Specific Mitogen-Activated Protein Kinase

Abstract

Smk1 is a meiosis-specific mitogen-activated protein kinase (MAPK) in yeast that controls spore differentiation. It is activated by a MAPK binding protein, Ssp2, upon completion of the meiotic divisions. The activation of Smk1 by Ssp2 is positively regulated by a meiosis-specific coactivator of the anaphase promoting complex (APC/C) E3 ubiquitin ligase, Ama1. Here, we identify Isc10 as an inhibitor that links APC/C Ama1 to Smk1 activation. Isc10 and Smk1 form an inhibited complex during meiosis I (MI).