Copy no. of housekeeping genes

Dom Spinella dspinella at
Tue Oct 21 19:29:59 EST 1997

> Hi Folks,
> Can anyone point me in the direction of or give me a rough idea as to
> what copy no. of B-actin, G3PDH and cyclophilin I should expect in say
> 1ug of total human RNA for any tissues they know of. I've looked in all
> the catalogues I have but can't find that info. or a source of that
> info.
> Many thanks.
> Duncan 


I checked out Ambion's website ( and picked up
some information in one of their technical bulletins (#151) relevant to
your question.  The claim is that all three "housekeeping" mRNAs are
present at a "moderate" abundance of ~0.1% of the total mRNA or about
0.3 pg of each message per ug of total RNA (which compares to ~0.003 -
0.03 pg/ug total RNA for "rare" mRNA species).  I usually assume about
200,000 mRNA molecules per cell, so you can calculate per cell copy
number accordingly.  The technical bulletin does provide references
which you may wish to follow up.  Hope that helps.
 -- Dom Spinella

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