Endocrine Abstracts

Growth hormone-releasing hormone (GHRH) and pituitary adenylate cyclase-activating polypeptide (PACAP) belong to the same superfamily of regulatory neuropeptides which also comprises VIP, glucagon, secretin and GIP. Both GHRH and PACAP have been characterized on the basis of their hypophysiotropic activities. In the course of vertebrate evolution, the primary structure of GHRH has markedly diverged while the sequence of PACAP has been remarkably well preserved. In mammals, GHR...

Pressure to conserve the primary structures of regulatory peptides during the evolution of vertebrates has been distinctly non-uniform. It is proposed that the major factor determining the extent to which the amino acid sequence of a peptide is conserved is the need to maintain high affinity binding to one or more specific receptors. In the case of peptides such as neuropeptide Y and somatostatin, that bind to multiple receptor subtypes via different signal epitopes, the compl...

Pituitary growth hormone (GH) like a number of other protein hormones, shows an episodic pattern of evolution, in which periods of prolonged near-stasis are interrupted by short bursts of rapid change. During mammalian evolution two episodes of rapid change of GH have been identified, one in the Artiodactyla and one in the Primates. The latter underlies the well known species specificity of human GH. Cloning and characterisation of GH genes for a number of mammalian species ha...

The cephalochordates (amphioxus) are the closest living invertebrate relatives of vertebrates, and have proved extremely useful for understanding the evolution of vertebrate genes and genomes. Molecular analysis in amphioxus has confirmed that vertebrates have a genome architecture that is fundamentally different from invertebrates. First, vertebrates have more genes than invertebrates. Second, vertebrates have many small multigene families (with 2 to 4 genes). Most of these a...