Differential expression of a gene for a methionine-rich storage protein in maize.
A methionine-rich 10 kDa zein storage protein from maize was isolated and the sequence of the N-terminal 30 amino acids was determined. Based on the amino acid sequence, two mixed oligonucleotides were synthesized and used to probe a maize endosperm cDNA library. A full-length cDNA clone encoding the 10 kDa zein was isolated by this procedure. The nucleotide sequence of the cDNA clone predicts a polypeptide of 129 amino acids, preceded by a signal peptide of 21 amino acids. The predicted polypeptide is unique in its extremely high content of methionine (22.5%). The maize inbred line BSSS-53, which has increased seed methionine due to overproduction of this protein, was compared to W23, a standard inbred line. Northern blot analysis showed that the relative RNA levels for the 10 kDa zein were enhanced in developing seeds of BSSS-53, providing a molecular basis for the overproduction of the protein. Southern blot analysis indicated that there are one or two 10 kDa zein genes in the maize genome.
D000595:Amino Acid Sequence; D001483:Base Sequence; D005796:Genes; D008715:Methionine; D008969:Molecular Sequence Data; D010944:Plants / Q000235:genetics*; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D014158:Transcription, Genetic; D003313:Zea mays / Q000235:genetics; D015028:Zein / Q000235:genetics*
D012313:RNA; D015028:Zein; D008715:Methionine