Regulation of ghrelin structure and membrane binding by phosphorylation

Peptides. 2008 Jun;29(6):904-11. doi: 10.1016/j.peptides.2008.02.001. Epub 2008 Feb 13.

Abstract

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Cell Membrane / metabolism*
  • Circular Dichroism
  • Gene Expression Regulation
  • Ghrelin / analysis
  • Ghrelin / chemistry*
  • Ghrelin / genetics
  • Ghrelin / metabolism*
  • Humans
  • Molecular Sequence Data
  • Peptide Hormones / analysis
  • Peptide Hormones / chemistry*
  • Peptide Hormones / genetics
  • Peptide Hormones / metabolism*
  • Phosphorylation
  • Protein Binding
  • Protein Structure, Secondary
  • Trifluoroethanol / chemistry

Substances

  • Ghrelin
  • Peptide Hormones
  • Trifluoroethanol