Structure and expression during the germination of rice seeds of the gene for a carboxypeptidase.

The carboxypeptidase gene from rice and corresponding cDNA clones were isolated. The Sal I 11.2 kb fragment of DNA cloned from a size-fractionated genome library contained eight introns and an open reading frame that encoded 500 amino acids (M(r) 55,445). The structure deduced for the carboxypeptidase from rice was very similar to those of type III serine carboxypeptidases from barley and wheat. The extent of homology of the amino acid sequence to that of these carboxypeptidases from barley and wheat was 92.3% and 87.2%, respectively. The accumulation of mRNA for the rice carboxypeptidase was conspicuous in germinating endosperms that contained aleurone layers, but levels were lower in leaves and roots. The abundance of the mRNA in endosperms was enhanced by gibberellic acid (GA) and accumulation of the mRNA was inhibited by abscisic acid (ABA). The rice gene for carboxypeptidase contained some pyrimidine boxes (C/TCTTTTC/T), in the 5' flanking region, which are a characteristic of a GA-responsive gene.