Figure 1. APC^Cdc20 is neither necessary not sufficient for complete Acm1 degradation at mitotic exit.

A) dbf2-2 cells expressing endogenous chromosomally tagged Clb5-3HA and Pds1-9Myc were released from a G1 arrest at 37°C and the levels of Clb5, Pds1, and Acm1 monitored by immunoblotting over the indicated time period. G6PD is a loading control. Numbers under each lane were obtained by fluorescence microscopic analysis of at least 100 cells at that timepoint stained with DAPI and scored for the presence of 2 segregated DNA masses indicative of the dbf2-2 late anaphase arrest point. cyc, asynchronous cycling cultures. B) Protein levels were quantified from the immunoblots in panel A. The abundance of each protein was plotted as a percentage of its maximal expression level. C) Extracts from synchronized cultures of yBRT135 (Wild-type) and mutant strain yBRT159 lacking several subunits of APC (apc2Δ apc11Δ cdc20Δ cdh1Δ pds1Δ clb5Δ SIC1^10x) were generously provided by David Toczyski [17], and were probed for Acm1, Clb2, and the loading control G6PD by immunoblotting. The budding index under each lane, taken from [17], is used as an indicator of cell cycle progression.