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Molecular evolution of prolactin in primates
O Caryl Wallis1, Akofa O Mac-Kwashie, Georgia Makri
1Biochemistry Department, School of Life Sciences, University of Sussex, Brighton, UK. C.Wallis@sussex.ac.uk
Journal of Molecular Evolution
|June 29, 2005
Summary
Primate prolactin evolved rapidly, showing significant changes in coding sequences due to positive selection. This accelerated evolution occurred after prosimians diverged but before New World monkeys split from other primates.
Area of Science:
- Molecular Evolution
- Primate Genetics
- Hormone Biology
Background:
- Protein hormones like prolactin and growth hormone (GH) exhibit episodic molecular evolution.
- Previous studies indicated a burst of rapid change in primate prolactin evolution.
Purpose of the Study:
- To precisely define the timing and nature of accelerated prolactin evolution in primates.
- To investigate the evolutionary pressures driving changes in prolactin genes.
Main Methods:
- Sequencing of prolactin gene coding regions from a prosimian (slow loris) and a New World monkey (marmoset).
- Comparative sequence analysis of prolactin genes across primate and non-primate species.
- Examination of gene duplication and regulatory region evolution.
Main Results:
- Slow loris prolactin sequence is similar to non-primate mammals, indicating rapid change occurred post-prosimian divergence.
- Marmoset prolactin sequence is similar to human prolactin, placing accelerated evolution before New World/Old World monkey divergence.
- Rapid changes were concentrated in mature prolactin coding sequences, suggesting positive adaptive selection without functional loss.
Conclusions:
- The burst of prolactin evolution in primates was driven by positive selection, primarily affecting the mature protein sequence.
- Prolactin gene duplication is not evident in early primates, unlike GH genes.
- Differential evolution of regulatory noncoding regions may occur in primate prolactin genes.