Related Experiment Video
Updated: Jun 17, 2026

A RAPID Method for Blood Processing to Increase the Yield of Plasma Peptide Levels in Human Blood
Published on: April 28, 2016
Ghrelin-like peptide with fatty acid modification and O-glycosylation in the red stingray, Dasyatis akajei
Hiroyuki Kaiya1, Shiho Kodama, Koutaro Ishiguro
1Department of Biochemistry, National Cardiovascular Center Research Institute, Osaka 565-8565, Japan. kaiya@ri.ncvc.go.jp
Background:
Ghrelin (GRLN) is now known to be an appetite-stimulating and growth hormone (GH)-releasing peptide that is predominantly synthesized and secreted from the stomachs of various vertebrate species from fish to mammals. Here, we report a GRLN-like peptide (GRLN-LP) in a cartilaginous fish, the red stingray, Dasyatis akajei.
Results:
The purified peptide contains 16 amino acids (GVSFHPQPRS10TSKPSA), and the serine residue at position 3 is modified by n-octanoic acid. The modification is the characteristic of GRLN. The six N-terminal amino acid residues (GVSFHP) were identical to another elasmobranch shark GRLN-LP that was recently identified although it had low identity with other GRLN peptides. Therefore, we designated this peptide stingray GRLN-LP. Uniquely, stingray GRLN-LP was O-glycosylated with mucin-type glycan chains [N-acetyl hexosamine (HexNAc)3 hexose(Hex)2] at threonine at position 11 (Thr-11) or both serine at position 10 (Ser-10) and Thr-11. Removal of the glycan structure by O-glycanase made the in vitro activity of stingray GRLN-LP decreased when it was evaluated by the increase in intracellular Ca2+ concentrations using a rat GHS-R1a-expressing cell line, suggesting that the glycan structure plays an important role for maintaining the activity of stingray GRLN-LP.
Conclusions:
This study reveals the structural diversity of GRLN and GRLN-LP in vertebrates.
Related Concept Videos
Regulation of Food Intake
Protein Modifications in the RER
Broadly, these modifications can be categorized into four main categories — glycosylation, formation of disulfide bonds, assembly of protein subunits, and specific proteolytic cleavages like removal of signal sequences.
Glucagon-like Receptor Agonists
GLP-1, when administered in high doses intravenously, triggers insulin secretion, inhibits glucagon release, slows gastric emptying, reduces food intake, and restores normal insulin secretion. However, its rapid inactivation by the...
Directing Proteins to the Rough Endoplasmic Reticulum
GPCRs Regulate Adenylyl Cylase Activity
Two...
Protein Folding Quality Check in the RER

