In Vitro Synthesis of the α and α′ Subunits of the 7S Storage Proteins (Conglycinin) of Soybean Seeds

Messenger RNAs (mRNAs), isolated from immature soybean ( Glycine max L., Merr.) seeds, that bound to oligo(dT)-cellulose were fractionated by centrifugation in sucrose density gradients containing dimethyl sulfoxide. mRNAs with sedimentation values between 21S and 25S coded for the in vitro translation of polypeptides with electrophoretic mobilities similar to those of the α′ and α subunits of the 7S seed storage protein. High pressure liquid chromatographic analyses of the trypsin-induced fragments (“column fingerprinting”) verified that the polypeptides produced in vitro were closely related to authentic α′ and α subunits. The fractions of RNA that coded for the in vitro synthesis of these subunits contained three major species of nonribosomal RNA (molecular weights of 1.1, 0.84, and 0.75 × 10 6 ) sufficiently large to code for the synthesis of the α′ and α subunits.