How+much+mRNA+in+total+RNA

How much mRNA in total RNA?

quote from pg 12 of Oligotex handbook (see Oligotex)

mRNA accounts for only 1–5% of the total cellular RNA although the actual amount depends on the cell type and physiological state.

also q

A typical mammalian cell contains 10–30 pg total RNA. The majority of RNA molecules, however, are tRNAs and rRNAs. mRNA accounts for only 1–5% of the total cellular RNA although the actual amount depends on the cell type and physiological state. Approximately 360,000 mRNA molecules are present in a single mammalian cell, with approximately 12,000 different mRNA species per cell. Some mRNAs comprise as much as 3% of the mRNA pool whereas others account for less than 0.01%. These “rare” or “low abundance” messages may have a copy number of only 5–15 molecules per cell. However, these rare species may account for as much as 11,000 different mRNA species, comprising 45% of the mRNA population. For more information, see Alberts, B. et al. (1994) Molecular Biology of the Cell, 3rd ed., New York: Garland Publishing, Inc. Due to the low proportion of mRNA in the total cellular RNA pool, reducing the amount of rRNA and tRNA in a total RNA preparation increases the relative amount of mRNA. mRNA enrichment is essential for construction of cDNA libraries and other applications where intact mRNA is highly desirable. The probability of selecting the right clone is greatly increased by reducing the amount of unwanted rRNA and tRNA. With pure, intact mRNA preparations, even low level messages can easily be detected by in vitro translation, northern hybridization, S1 analysis, expression-array and expression-chip analysis, or SAGE™ technology. Isolation of pure, intact mRNA is of great importance when characterizing mRNA species with these techniques.

Also see e-mail from Qiagen tech representative https://mail.google.com/mail/u/0/?ui=2&shva=1#label/Career/13bab3556e1483fe q

Thank you for contacting QIAGEN Technical Service. In a given total RNA population, you would expect anywhere between 1-3% mRNA. However, there are those rare-class transcripts which represent as low as 0.01% of the total RNA population. Therefore, you would expect at least 10 ug of mRNA in 1 mg of total RNA.

For more detailed information on the Oligotex kit, please click on the Handbook link from the website below. A discussion of mRNA in total RNA populations can be found on p. 12 of this handbook.

http://www.qiagen.com/products/rnastabilizationpurification/oligotexsystem/oligotexdirectmini.aspx#Tabs=t2