Single base substitution in growth hormone receptor gene influences the receptor density in bovine liver.
OBJECTIVE
Nucleotide sequence polymorphisms in the coding gene regions may influence the biological properties of proteins encoded by a gene. The A/T substitution in exon 8 of the growth hormone receptor (GHR) gene results in changed amino acid sequence 279 (Phe/Tyr) in the transmembrane domain of the receptor protein and therefore could influence its functional parameters. We searched for the relationship between the A/T nucleotide polymorphism in the GHR gene the receptor binding capacity and dissociation constant.


METHODS
Nucleotide sequence variations in the exon 8 (coding for the transmembrane domain of the receptor) of the bovine GHR gene and in fragments of adjacent introns were analysed using PCR-SSCP and sequencing techniques. GH receptor binding capacity (Bmax) and dissociation constant (Kd) for GHR were determined by the Scatchard analysis in livers of ten bulls carrying the AA or AT GHR genotypes.


RESULTS
Two single nucleotide polymorphisms (SNPs) were identified--the C/T transition in intron 8 at position 863+32 and the A/T transversion in exon 8 at position 836, the latter resulting in Phe/Tyr amino acid substitution in the receptor protein. The results showed significant differences in the GHR binding capacity between these genotypes. Bmax was significantly greater (p< or =0.01) in bulls carrying TT genotype of GHR in comparison to those with the AT genotype. No significant differences in the dissociation constants (Kd) were found.


CONCLUSIONS
Our results demonstrated that single base substitution in the transmembrane domain encoding region of GH receptor gene may influence the physiological properties of the receptor.
Maj
Andrzej
A
Department of Molecular Biology, Institute of Genetics and Animal Breeding, Polish Academy of Sciences, Jastrzebiec, 05-552 Wólka Kosowska, Poland.
Gajewska
Alina
A
Pierzchala
Mariusz
M
Kochman
Kazimierz
K
Zwierzchowski
Lech
L
D000818:Animals; D002417:Cattle; D005091:Exons; D005838:Genotype; D008099:Liver / Q000378:metabolism*; D008297:Male; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D011485:Protein Binding / Q000235:genetics; D011986:Receptors, Somatotropin / Q000235:genetics* / Q000378:metabolism*; D015398:Signal Transduction
D011986:Receptors, Somatotropin