TISSUE-SPECIFIC AND STAGE-SPECIFIC EXPRESSION OF A SOYBEAN (GLYCINE-MAX L.) SEED-MATURATION, BIOTINYLATED PROTEIN

A cDNA clone GmPM4 which encodes mRNA species in mature or dry soybean seeds was characterized. DNA sequence analysis shows that the deduced polypeptides have a molecular mass of 68 kDa. GmPM4 proteins have a r elatively high amino acid sequence homology with a major biotinylated protein isolated from pea seeds, SBP65, but both of these proteins dif fer markedly from that of presently known biotin enzymes. The accumula tion of GmPM4 mRNA is detectable in the leaf primodium and the vascula r tissues of the hypocotyl-radicle axis of mature seeds, and the GmPM4 proteins are present at high levels in dry and mature soybean seeds, but not in fresh immature seeds. It degrades rapidly at the early stag e of seed germination. These proteins are boiling-soluble and biotinyl ated when they are present endogenously in soybean seeds; however, the same recombinant protein expressed in Escherichia coli is boiling-sol uble, but it is not biotinylated.