Transcription factor IIA has been shown to interact with the TATA-binding protein and to act early during preinitiation complex formation. The human factor is composed of three subunits (oL, 13, 3,). A human cDNA clone encoding the largest subunit of TFIIA (oL) was isolated. The recombinant oL polypeptide, together with the 13 and 3' subunits, was capable of reconstituting TFIIA activity. Studies using antibodies raised against recombinant c~ polypeptide demonstrate that TFIIA can be an integral component of the preinitiation complex. We demonstrate that TFIIA not only interacts with TBP but also can associate with the TFIID complex. Functional assays establish that TFIIA has no apparent role in basal transcription but plays an important role in activation of transcription. Interestingly, amino acid sequence analyses of the 13-subunit demonstrate these residues to be entirely contained within the carboxyl terminus of the cDNA clone encoding the a-subunit.

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Pa'nzes strobus or P. resinom seedlings, 2 or 3 ears old, were illuminated in a closed chamber for 1 hour in the presence of c"&. This was followed by various periods up to 24 hours under different conditions of light and darkness. Then each seedling was divided into its shoot, stem, and roots, and these were extracted separately with 80% ethanol. The extracts were resolved first on resins into sugar, amino acid, and organic acid fractions and then resolved further by paper chromatography. The C14 content of various fractions and of the eluted comp u n d s was determined by plating and counting their aliquots. Ethanolinsolub%e residue was oxidized and counted as BaC140g.Eight hours after administration of the Cl4O3, 91 to 94% of the total C14 was found in the ethanol-soluble fractions of shoot, stem, or root. In shoots sugars were found to represent more than 95y0 of the ethanol-soluble photosynthate, with sucrose forming three-quarters of it. In stem and roots sucrose represented from 75 to 94% of the translocated photosynthate. Raffinose, glucose, and fructose were present in both stem and root.Seedlings with poorly developed root systems translocated less photosynthate to roots than those with good roots. Seedlings, which prior to the experiments were grown in full sunlight or 2500 ft-c artificial illumination translocated more photosynthate to roots than those grown in 6% of full sunlight or 250 ft-c artificial light. Stronger light during translocation itself also had a slight stirnulatory effect.Seedlings, which were illuminated in the presence of C1402 for 1 hour and then retained in a closed chamber for a further period of 7 hours, translocated a larger fraction of absorbed CI4 to their roots than comparable seedlings transferred to air after feeding C1400.'Manuscript