trans

C H A P T E R
4
Post-transcriptional regulation
Christine Clayton
Zentrum für Molekulare Biologie, Universität Heidelberg,
Heidelberg, Germany
INTRODUCTION
All medically important protist and helminth
parasites have to adjust to a variety of physical
and chemical conditions as they migrate to
various locations in the body and are transmitted
from one host to the next. To survive
and multiply in disparate environments, the
parasite must change its surface to combat
adverse chemical and physical conditions and
to minimize immune damage; it may build
and destroy specialized organelles and structures
needed for movement or invasion, and it
needs to switch its metabolism to exploit the
available substrates in aerobic or anaerobic
environments.
There are many possible stages, from gene to
protein, at which gene expression can be controlled.
These are illustrated in Figure 4.1. For
a model eukaryote, possible control points are:
1. Transcription initiation, elongation and
termination
2. Splicing patterns and efficiency
3. mRNA degradation in the nucleus
4. Polyadenylation
5. Nuclear export
6. mRNA translation
7. mRNA degradation in the cytoplasm
8. Protein folding
9. Protein modification and transport
10. Protein degradation.
This chapter considers control of steps 2 to 7.
Other issues were considered in Chapters
2 and 3.
WHY
POST-TRANSCRIPTIONAL
REGULATION?
Control of transcription initiation is essential
in nearly all organisms, but there are many
circumstances in which additional levels of regulation
are required. In complex eukaryotes,
Molecular Medical Parasitology
ISBN 0–12–473346–8
67
Copyright © 2003 Elsevier Science Ltd.
All rights of reproduction in any form reserved.