Summary: Plant Molecular Biology 44: 513527, 2000.
© 2000 Kluwer Academic Publishers. Printed in the Netherlands.
Two rice MADS domain proteins interact with OsMADS1
Jeongsim Lim, Yong-Hwan Moon, Gynheung An and Sung Key Jang
Division of Molecular and Life Science, Department of Life Science, Pohang University of Science and
Technology, San 31, Hyoja Dong, Pohang, Kyunghuk 790-784, Korea (author for correspondence; e-mail:
Received 21 December 1999; accepted in revised form 28 June 2000
Key words: leucine zipper motif, MADS box, protein-protein interaction, transcriptional activator
OsMADS1 is a MADS box gene controlling flower development in rice. In order to learn more about the function of
OsMADS1, we searched for cellular proteins interacting with OsMADS1 employing the yeast two-hybrid system.
Two novel proteins with MADS domains, which were named OsMADS14 and OsMADS15, were isolated from
a rice cDNA library. OsMADS14 and -15 are highly homologous to the maize MADS box gene ZAP1 which
is an orthologue of the floral homeotic gene APETALA1 (AP1). Interactions among the three MADS domain
proteins were confirmed by in vitro experiments using GST-fused OsMADS1 expressed in Escherichia coli and
in vitro translated proteins of OsMADS14 and -15. We determined which domains in OsMADS1, -14, and -15
were required for protein-protein interaction employing the two-hybrid system and pull-down experiments. While
the K domain was essential for protein-protein interaction, a region preceded by the K domain augmented this