Fig. 7.

Cyclin stability in extracts from mitotic and endoreduplicating endosperm cells. Radio-labeled proteins synthesized in vitro were incubated with extracts from endosperm at different stages of development. Reaction products were separated by SDS-PAGE, and gels were exposed to X-ray films. Incubation times are indicated in minutes. a Stability of CYCB1;3 in 7-, 11-, and 15-DAP endosperm extracts. b Stability of CYCA1;1, CYCD5;1, CYCD2;1, 27-kDa γ-zein, and firefly luciferase in 7- and 15-DAP endosperm extracts. c Time-course analysis of cyclin degradation in 7-DAP endosperm extract and its inhibition by the proteasome inhibitor, MG-132; (+) and (−) symbols indicate presence or absence of MG-132, respectively