Two different members of the phosphoenolpyruvate carboxylase(PEPC)-encoding multigene family (clones lambda-CP21 and lambda-CP46) have been isolated from a Sorghum vulgare lambda-EMBL4 genomic library. The use of the 3'-noncoding regions to probe Northern blots of RNA from roots, etiolated leaves and green leaves indicated that lambda-CP21 and lambda-CP46 encode the C3- and C4-type leaf PEPC isoforms, respectively. The lambda-CP21 clone is expressed in the three tissues and is not light-regulated, whereas lambda-CP46 is only expressed in greening leaves. The nucleotide sequence of the 5'-flanking DNA (520 bp) has been determined for both genes. For lambda-CP46, several direct repeats were located in this region with similarities to sequences found in other light-regulated genes, but not in lambda-CP21. The deduced amino acid sequences of the two S. vulgare PEPC proteins are 75% identical.
