Characterization of oligo(dT)-binding proteins from seedlings of winter wheat

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Abstract
Oligo(dT)-binding proteins of winter wheat (Triticum aestivum L.) seedlings were separated into two fractions by chromatography on oligo(dT)-cellulose; one fraction was eluted sequentially with 10 mM Tris-HCl (D fraction) and the other was eluted with the same buffer supplemented with 500 g L-1 formamide (formamide fraction). The proteins associated with the oligo(dT)-cellulose were characterized by SDS-polyacrylamide gel electrophoresis (PAGE) and, out of the more than 17 polypeptides present in the fractions, a set of proteins common to both the D and formamide fractions had an apparent molecular mass of 55 kDa. Two other sets of the isoform proteins with a molecular mass of 35 and 29 kDa, respectively, were present in the formamide fraction. After growth under snow for three months, an apparent increase in the level of polypeptide with a molecular mass of about 80-kDa was detected. Studies with a cell-free translation system showed that the addition of each fraction resulted in a 1.7- to 3.8-fold stimulation of the rate of incorporation of L-[35S]-methionine into acid-insoluble material relative to the control rate (without addition). The nature of the products of translation and the efficiency of their synthesis were influenced by the presence of added oligo(dT)-binding proteins. It is suggested that oligo(dT)-binding proteins of winter wheat seedlings are involved in the regulation of the translational activity of poly(A)+ RNA.