Characterization and partial amino acid sequence of a high molecular weight protein from rice seed endosperm: Homology to pyruvate orthophosphate dikinase

Abstract

Summary Endosperm protein of immature rice ( Oryza sativa L.) seed was characterized by two-dimensional gel electrophoresis. A promiment spot corresponding to a protein of about 94 kD and isoelectric point of 6.0 was observed. The 94 kD protein was electroblotted onto a PVDF membrane and the N-terminal amino acid sequence was determined. Proteins of the internal amino acid sequences of the 94 kD protein were determined by sequence analyses of peptides obtained by Cleveland peptide mapping. The N-terminal and internal amino acid sequences, when compared with those in a protein data base, showed that the 94 kD protein was significantly similar to the PPDK of maize. There were no intradisulfide bonds or N-linked oligosaccharide chains in the molecule. The PPDK from maize leaves cross-reacted with antiserum raised against the 94 kD protein of rice seed endosperm. These results suggest that the 94 kD protein of rice seed endosperm is structurally homologous with PPDK.