Open AccessA novel protein programmed by the mRNA conserved in dry wheat embryos
Author(s) -
HANLEYBOWDOIN Linda,
LANE Byron G.
Publication year - 1983
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1983.tb07611.x
Subject(s) - cysteine , wheat germ agglutinin , biochemistry , messenger rna , embryo , protein biosynthesis , biology , acetamide , microbiology and biotechnology , polyacrylamide gel electrophoresis , chemistry , enzyme , gene , lectin , astrobiology
If bulk mRNA from dry wheat embryos (wheat germ) is used to direct cell‐free incorporation of [ 35 S]cysteine into proteins, a striking proportion of the total radioactivity is channeled into a single protein. During early postimbibition development, when protein synthesis is directed by the mRNA conserved in dry embryos, incorporation of cysteine is preponderantly (20–25%) directed into synthesis of this one protein: the ‘early’ cysteine‐labeled protein (E c ). When conserved mRNA from the dry embryos has been fully degraded, as when cellular or cell‐free protein synthesis is directed by the mRNA in germinated embryos, synthesis of E c is not detected. Reliable detection of E c requires prior alkylation of wheat embryo proteins, and it was especially interesting to find that when wheat embryo proteins are alkylated by iodo[ 14 C]acetamide, two proteins co‐dominate the distribution of radioalkylated products in dodecylsulphate/polyacrylamide gels: E c and wheat germ agglutinin. Using co‐electrophoresis with the isotopically labeled protein to detect a dye‐staining counterpart, E c has been purified by combined cation‐exchange and gel‐filtration chromatography of alkylated wheat germ proteins. The purified protein can be recovered in milligram quantity (5–10 mg/100 g wheat germ) and compositional analysis shows that it is unusually rich in cysteine (approx. 15%) and glycine (approx. 17%), as is wheat germ agglutinin.