Michael Wallis

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In mammals pituitary growth hormone (GH) shows a slow basal rate of evolution (0.22 ± 0.03 × 10−9 substitutions/amino acid site/year) which appears to have increased by at least 25–50-fold on two occasions, during the evolution of primates (to at least 10.8 ± 1.3 X 10−9 substitutions/amino acid site/year) and artiodactyl ruminants (to at least 5.6 ± 1.3 X(More)
In most mammals pituitary GH is encoded by a single gene with no close relatives. However, in man the GH gene has been shown to be one of a cluster of five closely related genes, four of which are expressed in the placenta. Rhesus monkey also expresses at least five closely related GH-like genes, although the genomic organisation of these has not been fully(More)
Pituitary growth hormone (GH), like several other protein hormones, shows an unusual episodic pattern of molecular evolution in which sustained bursts of rapid change are imposed on long periods of very slow evolution (near-stasis). A marked period of rapid change occurred in the evolution of GH in primates or a primate ancestor, and gave rise to the(More)
In mammals the sequence of pituitary growth hormone (GH) is generally strongly conserved, indicating a slow basal rate of molecular evolution. However, on two occasions, during the evolution of primates and that of cetartiodactyls, the rate of evolution has increased dramatically (25 to 50-fold) so that the sequences of human and ruminant GHs differ(More)
Growth hormone, prolactin, the fish hormone, somatolactin, and related mammalian placental hormones, including placental lactogen, form a family of polypeptide hormones that share a common tertiary structure. They produce their biological effects by interacting with and dimerizing specific single transmembrane-domain receptors. The receptors belong to a(More)
Pituitary growth hormone shows a pattern of molecular evolution in which occasional bursts of rapid change are imposed on a slow basal rate. It is suggested that these bursts of rapid evolution are a consequence of acquisition by this protein hormone of a secondary function, the importance of which varies. As the function of the hormone switches to(More)
The sequences of ovine and bovine placental lactogens (based on published cDNA sequences) are remarkably different, indicating a very rapid rate of evolution. Analysis of the cDNA sequences indicates that the rate of nonsynonymous substitution in these proteins is considerably greater than the rate of synonymous substitution. This is an unusual situation,(More)
Previous studies have shown that pituitary growth hormone displays an episodic pattern of evolution, with a slow underlying evolutionary rate and occasional sustained bursts of rapid change. The present study establishes that pituitary prolactin shows a similar pattern. During much of tetrapod evolution the sequence of prolactin has been strongly conserved,(More)
The insulin-like growth factors (IGF-I and IGF-II) and insulin are related proteins that play an important role in regulation of metabolism and growth. In mammals these proteins are generally strongly conserved, though the sequence of insulin underwent periods of rapid change during the evolution of hystricomorph rodents and new-world monkeys (NWM). The(More)