size of ribosomal RNAs ?

David F. Spencer dspencer at
Tue Mar 10 14:17:03 EST 1998

In article <34FE5D63.1D8 at>, maiwald at wrote:

> Thanks for all answers so far.
> Maybe I should add that I work with barley RNA. The nearest hit I could
> find myself (after I had posted my question) is for maize chloroplast
> rRNA:
>         "big" rRNA   : 2900
>         "small" rRNA : 1491

It is fairly easy to predict the sizes of the ribosomal RNA's in barley
even though only the 5.8S cyto sequence for barley has been determined. 
The rRNAs of angiosperms in general and monocots specifically don't vary
much in size.

For cytosolic rRNAs (nuclear-encoded):

17S/18S (SSU) : 1805-1810
25S/26S (LSU) : 3380 +- 10
5.8S          : 162-163
5S            : 119 +- 1

For the chloroplast rRNAs (which will be much less abundant in total cell RNA):

16S  : 1490-1500
23S  : 2850 +- 50
5S   : 120
4.5S : 95-96 (sequence available for barley; is as large as 104 in others)

In formaldehyde gels the rRNA mobilities are generally fairly reliable
although in general rRNAs wouldn't be particularly good choices for markers
because of their frequently quite resilient secondary structure.


David F. Spencer, PhD
Dept. Of Biochemistry
Dalhousie University
Halifax, Nova Scotia

dspencer at
dspencer at

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