Regulation of ghrelin structure and membrane binding by phosphorylation.
The peptide hormone ghrelin requires Ser-3 acylation for receptor binding, orexigenic and anti-inflammatory effects. Functions of desacylghrelin are less well understood. In vitro kinase assays reveal that the evolutionarily conserved Ser-18 in the basic C-terminus is an excellent substrate for protein kinase C. Circular dichroism reveals that desacylghrelin is approximately 12% helical in aqueous solution and approximately 50% helical in trifluoroethanol. Ser-18-phosphorylation, Ser-18-Ala substitution, or Ser-3-acylation reduces the helical character in trifluoroethanol to approximately 24%. Both ghrelin and desacylghrelin bind to phosphatidylcholine:phosphatidylserine sucrose-loaded vesicles in a phosphatidylserine-dependent manner. Phosphoghrelin and phosphodesacylghrelin show greatly diminished phosphatidylserine-dependent binding. These results are consistent with binding of ghrelin and desacylghrelin to acidic lipids via the basic face of an amphipathic helix with Ser-18 phosphorylation disrupting both helical character and membrane binding.
Dehlin
Eva
E
Department of Anesthesiology, University of Virginia, Charlottesville, VA 22908, United States.
Liu
Jianhua
J
Yun
Samuel H
SH
Fox
Elizabeth
E
Snyder
Sandra
S
Gineste
Cyrille
C
Willingham
Leslie
L
Geysen
Mario
M
Gaylinn
Bruce D
BD
Sando
Julianne J
JJ
D000595:Amino Acid Sequence; D002462:Cell Membrane / Q000378:metabolism*; D002942:Circular Dichroism; D005786:Gene Expression Regulation; D054439:Ghrelin / Q000032:analysis / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D036361:Peptide Hormones / Q000032:analysis / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D017433:Protein Structure, Secondary; D014270:Trifluoroethanol / Q000737:chemistry
D054439:Ghrelin; D036361:Peptide Hormones; D014270:Trifluoroethanol