Isolation and cDNA cloning of a novel galanin-like peptide (GALP) from porcine hypothalamus.
Galanin is a widely distributed neuropeptide with a variety of physiological functions. Three galanin receptor subtypes, GALR1, GALR2, and GALR3, have been reported. We isolated a novel galanin-like peptide (GALP) from porcine hypothalamus by observing its activity for increasing [(35)S]GTPgammaS binding to a membrane preparation of GALR2-transfected cells. The peptide had 60 amino acid residues and a non-amidated C terminus. The amino acid sequence of GALP-(9-21) was completely identical to that of galanin-(1-13). A cloned porcine GALP cDNA indicated that GALP was processed from a 120-amino acid GALP precursor protein. The structures of rat and human GALP-(1-60) were deduced from cloned cDNA, which indicated that the amino acid sequences 1-24 and 41-53 were highly conserved between humans, rats, and pigs. Receptor binding studies revealed that porcine GALP-(1-60) had a high affinity for the GALR2 receptor (IC(50) = 0.24 nM) and a lower affinity for the GALR1 receptor (IC(50) = 4.3 nM). In contrast, galanin showed high affinity for the GALR1 (IC(50) = 0.097 nM) and GALR2 receptors (IC(50) = 0.48 nM). GALP is therefore an endogenous ligand that preferentially binds the GALR2 receptor, whereas galanin is relatively non-selective.
Ohtaki
T
T
Discovery Research Laboratories I, Pharmaceutical Discovery Research Division, Takeda Chemical Industries, Ltd., Wadai 10, Tsukuba, Ibaraki 300-4293, Japan. Ohtaki_Tetsuya@takeda.co.jp
Kumano
S
S
Ishibashi
Y
Y
Ogi
K
K
Matsui
H
H
Harada
M
M
Kitada
C
C
Kurokawa
T
T
Onda
H
H
Fujino
M
M
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016466:CHO Cells; D003001:Cloning, Molecular; D006224:Cricetinae; D018076:DNA, Complementary / Q000737:chemistry / Q000302:isolation & purification*; D019004:Galanin / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D007031:Hypothalamus / Q000737:chemistry*; D008969:Molecular Sequence Data; D051381:Rats; D044088:Receptors, Galanin; D018013:Receptors, Neuropeptide / Q000819:agonists; D013552:Swine
D018076:DNA, Complementary; D044088:Receptors, Galanin; D018013:Receptors, Neuropeptide; D019004:Galanin