Measurement of a stimulatory protein of RNA polymerase II in various mouse organs by the complement fixation test

Transcriptional fidelity and proofreading by RNA polymerase II

We have addressed whether the intrinsic 3'-->5' nuclease activity of human RNA polymerase II (pol II) can proofread during transcription in vitro. In the presence of SII, a protein that stimulates the nuclease activity, pol II quantitatively removed misincorporated nucleotides from the nascent transcript during rapid chain extension. The basis of discrimination between the correct and incorrect base was the slow addition of the next nucleotide to the mismatched terminus. Incorporation of inosine monophosphate inhibited next nucleotide addition by a similar magnitude as a mismatched base. We used this finding to demonstrate that addition of SII to a transcription reaction dramatically altered the RNA base content, reflecting the stable incorporation of more "correct" (GMP) and fewer "incorrect" (IMP) nucleotides.

Modulation of nonglobin mRNA levels in erythropoiesis

During erythropoiesis, the decrease of complexity of a RNA population is an important process as is globin mRNA accumulation. To determine the sequential control process of gene expression, many genomic clones which express in mouse reticulocytes were obtained and used for the titration of each mRNA level in the different stages of erythroid cells. The level of mRNAs of rt-clones decreases depending on the maturation of erythroid cells, and the coordinated and sequential control of this level is likely to be one of the factors affecting this process.