RAP-1 IS AN ARABIDOPSIS MYC-LIKE R-PROTEIN HOMOLOG, THAT BINDS TO G-BOX SEQUENCE MOTIFS

An Arabidopsis cDNA clone encoding a DNA-binding protein, RAP-1, was i solated by southwestern screening of an Escherichia coli cDNA expressi on library. The protein contains a bHLH DNA-binding domain and is homo logous to R proteins, regulating anthocyanin biosynthesis. RAP-1 binds to the sequence CACNTG. It is encoded by a single gene, which is expr essed to high levels in root and stem and to low levels in leaf and fl ower. No expression could be detected in siliques. Rap-1 does not corr espond to one of the known loci involved in anthocyanin biosynthesis, since it is located at a different map position. In contrast to the ma ize R protein Lc, RAP-1 did not induce anthocyanin biosynthesis in pea cotyledons. Thus, RAP-1 is a novel member of the bHLH class of DNA-bi nding proteins.