Evolution of gnathostome prodynorphin and proenkephalin: characterization of a shark proenkephalin and prodynorphin cDNAs.
Analyses of prodynorphin and proenkephalin cDNAs cloned from the central nervous system of the shark, Heterodontus portusjacksoni, provided additional evidence that these two opioid precursor-coding genes were most likely directly derived from a common ancestral gene. The two cDNAs could be aligned by inserting only seven gaps. The prodynorphin cDNA encodes five opioid sequences which could be aligned to opioid positions B through F in the proenkephalin cDNA. The sequence identity within the opioid positions was 59% at the amino acid level. Shark α-neo-endorphin, dynorphin A, and dynorphin B have amino acid motifs in common with shark met-enkephalin-8, and shark proenkephalin opioid positions E and F, respectively, which have not been observed in other gnathostome prodynorphin and proenkephalin precursor sequences. Shark prodynorphin encodes both kappa (α-neo-endorphin, dynorphin A, and dynorphin B) and delta (met-enkephalin and leu-enkephalin) opioid sequences. Mixed function prodynorphin precursors (encoding both enkephalins and dynorphins) are also found in representatives of the teleost fishes, lungfishes, and amphibians. It appears that only mammals evolved a prodynorphin precursor that exclusively encodes kappa opioid agonists (dynorphins).
University of Denver, Department of Biological Sciences, Denver, CO 80210, USA.
Leanne K
LK
Komorowski
Stephanie G
SG
Lecaude
Christian G
CG
Westring
Phillip B
PB
Danielson
Robert M
RM
Dores
D000818:Animals; D018076:DNA, Complementary / Q000235:genetics; D004745:Enkephalins / Q000235:genetics / Q000378:metabolism*; D019143:Evolution, Molecular; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism*; D012754:Sharks / Q000235:genetics / Q000378:metabolism*
D018076:DNA, Complementary; D004745:Enkephalins; D011498:Protein Precursors; C029992:proenkephalin; C033660:preproenkephalin