Processing of Eukaryotic mRNA

(Lodish et al., 2000, Section 11.2, 11.3)

Overview of mRNA processing in eukaryotes (Fig. 11.7).

5' ends of RNA transcripts are capped with 7'-methylguanylate (m7G) (Fig. 11.8).

3' ends of RNA transcripts made by RNA polymerase II are cleaved and polyadenylated at specific sites (Fig. 11.12).

mRNA Splicing of Exons

Binding sites for 5' and 3' splice sites (Fig. 11.17).
Splicing occurs via two transesterification reactions (Fig. 11.16).
The spliceosomal splicing cycle (Fig. 11.19).
Almost all functional mRNAs are derived by splicing together exons from the same RNA transcript. In two types of protozoa and euglenoids mRNAs are constructed by splicing together exons from separate RNA and is called trans-splicing.
Splicing can be regulated such that there are cell-type specific splicing.

Fibronectin (Fig. 11.24).
Expression of Sex-lethal protein during Drosophila embryogenesis (Fig. 11.25).
Chicken cochlear basal cells respond to varying concentrations of Ca2+ by adapting one of 576 possible splicing combinations to give a characteristic isotype of the slo gene product (Fig. 11.27).

Activity

Quiz

References:
Lodish, H., Berk, A., Zipursky, S.L., Matsudaira, P., Baltimore, D., Darnell, J., 2000, Molecular Cell Biology, 4th Ed., W.H. Freeman and Company, NY, New York. ISBN 0-7167-3136-3.