Neuropeptides, structural similarities

Neuropeptides are often grouped by their structural similarity or tissue source. Among these are the hypothalamic releasing factors (e.g., corticotrophin-releasing factor [CRF], thyrotropin-releasing hormone), anteior pituitary hormones (e.g., adrenocorticotrophic hormone [ACTFI], follicle-stimulating hormone [FSFI]), and posterior pituitary hormones... 

Naunyn-Schmiedeberg s Arch Pharmacol 338 368-72 Szabo B, Hedler L, Starke K (1989) Facilitation of the release of noradrenaline an extra-adrenal effect of adrenocorticotropic hormone. Resuscitation 18 229-42 Tatemoto K (2004) Neuropeptide Y history and overview. In Michel MC (ed) Neuropeptide Y and related peptides, Handbook of Experimental Pharmacology, vol 162. Springer, Berlin, pp 1-21 Tatemoto K, Carlquist M, Mutt V (1982) Neuropeptide Y - a novel brain peptide with structural similarities to peptide YY and pancreatic polypeptide. Nature 296 659-60... 

Figure 1 Examples of insect and crustacean neuropeptides of similar structure with the same or different functions. Pandanus borealis is a shrimp. pGlu, pyroglutamic acid.

Additional myotropic/inhibitory neuropeptide structures will be characterized on the basis of immunological similarity to vertebrate and invertebrate peptide structures, and also with the techniques of molecular biology. Two initial successes with those methods are discussed in this report (17,25). In addition, antibodies raised against FMRFamide were used to isolate and structurally characterize a nonapeptide containing C-terminal FMRFamide from head extracts of Drosophila (26). Subsequently, the gene that codes for this nonapeptide and eight other FMRFamide-related structures was isolated and sequenced (27,28). 

Vertebrate-like neuropeptides are present in insects as demonstrated immunologically, and probably vice versa, but it is unclear what the function is for these peptides in their heterologous animal system. The structural similarities between these molecules suggest that common, biologically-active ancestral molecules may have existed and evolved to perform different functions depending on the physiological diversity and needs of the animals involved. 

Tatemoto, K., Carlquist, M. Mutt, Y (1982) Neuropeptide Y - a novel brain peptide with structural similarities to peptide YY and pancreatic polypeptide. Nature 296, 659-660. 

JH in insects maintains larval and nymphal characteristics during development and suppresses metamorphosis into the adult form similarly, MF in crustaceans retards metamorphosis and larval development [123]. Two types of neuropeptides control the production of JH in the CAs of insects in vitro (a) allatotropins, which stimulate the biosynthesis of JH and have only been found in insects to date, and (b) allatostatins (ASTs) which, inter alia, inhibit the biosynthesis of JH but which also have numerous other effects (mainly myoinhibitory) [137]. Neuropeptides that are structurally similar to the ASTs are also present in crustaceans and, therefore, we will review here what is known from the ASTs of insects and crustaceans. 

Many neuropeptides were originally identified as pituitary or gastrointestinal hormones 317 Peptides can be grouped by structural and functional similarity 317 The function of peptides as first messengers is evolutionarily very old 318 Various techniques are used to identify additional neuropeptides 319 The neuropeptides exhibit a few key differences from the classical neurotransmitters 319... 

Peptides can be grouped by structural and functional similarity. Although the list of neuropeptides is already quite long, as seen in the partial listing in Figure 18-1,... 

Based upon similarity of structure and activity, Pea-HGH-I and II are classified as members of the AKH/RPCH family of neuropeptides. 

The similarity of the crustacean blanching substance (Factor A) found in crustacean sinus glands and insect corpora cardiaca has been confirmed by the structural identification of a family of neuropeptides common to arthropods. The first identified member of this family is RPCH (red pigment concentrating hormone), an octapeptide (pGlu-Leu-Asn-Phe-Ser-Pro-Gly-Trp-amide) isolated from eyestalks of the shrimp Pandalus borealis (28). Shortly thereafter, a related peptide--designated as adipokinetic hormone (AKH)--was purified from locust... 

Figure 3. Schematic diagram of structural relationships between vertebrate and invertebrate neuropeptides discussed in the text. The similarity in sequences suggests that they may have been derived from a common ancestral source.

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