Pane 1. In the 1970s, Carol Gross and colleagues discovered a protein required f
ID: 268149 • Letter: P
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Pane 1. In the 1970s, Carol Gross and colleagues discovered a protein required for the expression of "heat shock proteins" that help protect the cell from effects of high temperature. They purified the 32kDa protein (HtpR) and identified it as a sigma factor. They then produced an RNA polymerase that was lacking sigma70 (o 70) but instead contained HtpR. To find out whether the HtpR protein could direct RNA synthesis from promoters of heat shock proteins, they constructed a plasmid with two of these promoters (P1 and P2) and then detected RNA molecules produced from these promoters. Transcription from these promoters would generate RNA transcripts with lengths of 220 and 140 nucleotides, respectively. The results are shown below. 2 34Mnt -622 -527 Agarose gel used to detect RNA products by in vitro transcription. -404 Lanes 1 and 3- RNA pol with HtpR Lanes 2 and 4-RNA pol with ? 70 -309 217 190 160 Source Grossman, A.D. Eickson, J.W and Gross, CA The htpR Gene Product of E cos is a Sigma Factor for Heat Shock Promoters Cell Vol 38, 383-390, September 1984, with permssion rom Elsevier Courtesy Carol Gross What conclusion can you draw from the data? 4 ptsExplanation / Answer
The agarose gel conclude that, PI at lane 1 contains less RNA pol with Htpr and is less present/expressed in comparision of lane 3. IT means lane 3 has better quality of RNA pol with Htpr. and it also conclude that Lane 2 and Lane for donot expresses anything it means RNA pol with sigma factor are present there and no Htpr.
while, P2 at lane 1, forms smear which means there occurs a contamination in the sample, in Lane 2 and lane 4 sigma factor in RNA pol are present, and lan 3 express good quantity of RNA pol with Htpr.
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