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/lp/oxford-university-press/convergent-evolution-of-cysteine-residues-in-sperm-protamines-of-one-YzD20c6a4z
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- Publisher
- Oxford University Press
- ISSN
- 0737-4038
- eISSN
- 1537-1719
- DOI
- 10.1093/oxfordjournals.molbev.a040247
- Publisher site
- See Article on Publisher Site
Abstract
Abstract A characteristic feature of the sperm P1 protamines of eutherian mammals is the constant presence of six to nine cysteine residues per molecule. During spermiogenesis these residues become oxidized to form a three-dimensional network of disulfide bridges between, and within, protamine molecules in the sperm chromatin. This covalent cross linking strongly stabilizes eutherian sperm nuclei. In contrast, protamines sequenced from teleost fish, birds, monotremes, and marsupials all lack cysteine residues and their sperm nuclei, without the stabilizing cross links, are easily decondensed in vitro. We have now found that one genus of tiny, shrewlike dasyurid marsupials, the Planigales, possess P1 protamines containing five to six cysteine residues. These residues appear to have evolved since the divergence of Planigales from other members of the family Dasyuridae, such as the marsupial mouse, Sminthopsis crassicaudata. We believe this constitutes a case of convergent evolution in a subfamily of dasyurid marsupials toward the cysteine-rich eutherian form of sperm protamine P1. This content is only available as a PDF.
Journal
Molecular Biology and Evolution – Oxford University Press
Published: Jul 1, 1995