Molecular cloning and characterization of cDNA for a rice protein that contains seven repetitive segments of the Trp-Asp forty-amino-acid repeat (WD-40 repeat).

A cDNA clone for a polypeptide that contained seven repetitive segments of the Trp-Asp forty-amino-acid repeat (WD-40 repeat) was isolated from a cDNA library prepared from the greening leaves of rice. The cDNA was 1,285 bp long and contained an open reading frame that encoded a protein of 334 amino acid residues, which was designated it RWD (rice protein containing the WD-40 repeat). RWD exhibited greater homology to a group of receptor for activated C-kinase (RACK), a product of auxin-regulated gene from cultured cells (arcA) and a Chlamydomonas beta subunit-like polypeptide (Cblp) rather than to the beta subunits of heterotrimeric G protein complexes. The mRNA for RWD (1.3 kb) was found in all organs of rice plants, in particular, in roots. Therefore, RWD is suggested to be a protein that is expressed constitutively.