Ribulose-1,5-bisphosphate carboxylase/oxygenase from Zea mays: amino-acid sequence of the small subunit

The amino-acid sequence of the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase from Zea mays has been determined by alignment of peptides generated by digestion with trypsin, chymotrypsin, staphylococcal protease and thermolysin. The protein-chemically determined structure is in complete agreement with the nucleotide-derived sequence as published recently (Matsuoka et al. (1987) J. Biochem. 102, 673-676), but in addition possesses, however, sixteen experimentally verified dimorphies at various positions and possibly nine more for which evidence is tentatively pointing to two (or more) different expressed nuclear genes for the small subunit. These protein dimorphies represent a protein family corresponding to a gene family, the components of which have not been separated. The closest homologous polypeptide is the small subunit from wheat.