Structural Analysis of Nuclear Genes Coding for the Precursor to the Small Subunit of Wheat Ribulose-1,5-Bisphosphate Carboxylase

We have isolated and characterized a full-length cDNA clone encoding the precursor to the small subunit of wheat ribulose-1,5-bisphosphate carboxylase. From the nucleotide sequence, we deduce that the precursor contains the mature small subunit of 128 amino acid residues and an amino-terminal transit sequence of 47 amino acid residues. Southern blot analysis reveals that the small subunit precursor is encoded by a multigene family. One member of the family has been isolated. Nucleotide sequence and R-loop analyses show that it contains only one intron which separates the coding sequence of the transit peptide from that of the mature protein. This gene is expressed in vivo, as shown by mRNA hybridization to a specific probe from its 3′ non-coding region.