Purification and characterization of feline ghrelin and its possible role.
Ghrelin, a novel 28-amino acid peptide with an n-octanoyl modification at Ser3, has been isolated from rat and human stomach as an endogenous ligand for the growth hormone secretagogue receptor. Here, we purified feline ghrelin and examined its possible physiological role in cats. The major active form of feline ghrelin is a 28-amino acid peptide octanoylated (C8:0) at Ser3; except for one amino acid residue replacement, this structure is identical to those of rat and human ghrelins. However, much structural divergence in peptide length and fatty acid modification was observed in feline ghrelin: peptides consisting of 27 or 26 amino acids lacking Gln14 and/or Arg28 were found, and the third serine residue was modified by octanoic acid (C8:0), decanoic acid (10:0), or unsaturated fatty acids (C8:1, C10:1 and C10:2). In agreement with the structural divergence, two kinds of cDNA with different lengths were isolated. Administration of synthetic rat ghrelin increased plasma growth hormone levels in cats, with a potency similar to that in rat or human. Plasma levels of ghrelin in cats increased approximately 2.5-fold after fasting. The present study indicates the existence of structural divergence in feline ghrelin and suggests that, as in other animals, ghrelin may play important roles in GH release and feeding in cats.
Ida
Takanori
T
Department of Veterinary Physiology, Faculty of Agriculture, University of Miyazaki, Miyazaki 889-2155, Japan.
Miyazato
Mikiya
M
Naganobu
Kiyokazu
K
Nakahara
Keiko
K
Sato
Miho
M
Lin
Xing-Zi
XZ
Kaiya
Hiroyuki
H
Doi
Kentaro
K
Noda
Soushi
S
Kubo
Ayako
A
Murakami
Noboru
N
Kangawa
Kenji
K
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002415:Cats; D002851:Chromatography, High Pressure Liquid; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D004797:Enzyme-Linked Immunosorbent Assay; D005215:Fasting; D054439:Ghrelin; D013006:Growth Hormone / Q000097:blood; D007700:Kinetics; D008969:Molecular Sequence Data; D036361:Peptide Hormones / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology*
D018076:DNA, Complementary; D054439:Ghrelin; D036361:Peptide Hormones; D013006:Growth Hormone