Structural determination and histochemical localization of ghrelin in the red-eared slider turtle, Trachemys scripta elegans.
We purified ghrelin peptide and determined the cDNA sequence encoding the precursor protein from the stomach of the red-eared slider turtle, Trachemys scripta elegans. The Trachemys ghrelin is comprised of 25-amino acids and has the sequence GSSFLSPEYQNTQQRKDPKKHTKLN. The third serine residue was modified by n-octanoic (C8:0), decanoic (C10:0) or unsaturated decanoic acid (C10:1). The carboxyl-terminal end of the peptide was not amidated, as seen in the ghrelins of other land vertebrates. Quantitative real-time PCR analysis revealed high levels of gene expression in the stomach and moderate levels in the large intestine and pancreas. Histochemical studies of turtle stomach revealed that ghrelin-immunopositive (ghrelin-ip) cells, which were small and round, were observed in the mucosal layer of the stomach but not in the myenteric plexus, and ghrelin-mRNA-expressing (ghrelin-ex) cells detected by in situ hybridization were scattered in a similar distribution as ghrelin-ip cells. These results indicate that ghrelin is present in reptiles.
Kaiya
Hiroyuki
H
Department of Biochemistry, National Cardiovascular Center Research Institute, 5-7-1 Fujishirodai, Suita, Osaka 565-8565, Japan. kaiya@ri.ncvc.go.jp
Sakata
Ichiro
I
Kojima
Masayasu
M
Hosoda
Hiroshi
H
Sakai
Takafumi
T
Kangawa
Kenji
K
D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D018076:DNA, Complementary / Q000096:biosynthesis / Q000235:genetics; D005753:Gastric Mucosa / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology; D054439:Ghrelin; D007150:Immunohistochemistry; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D036361:Peptide Hormones / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013270:Stomach / Q000033:anatomy & histology / Q000166:cytology; D014426:Turtles / Q000502:physiology*
D018076:DNA, Complementary; D054439:Ghrelin; D015345:Oligonucleotide Probes; D036361:Peptide Hormones; D012333:RNA, Messenger