Identification of amino-acids in the α-subunit first and third loops that are crucial for the heterospecific follicle-stimulating hormone activity of equid luteinizing hormone/choriogonadotropin

M. Chopineau; N. Martinat; J. F. Gibrat; C. Galet; F. Lecompte; F. Foulon-Gauze; C. Pourchet; F. Guillou; Y. Combarnous

doi:10.1530/eje.0.1500877

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Identification of amino-acids in the α-subunit first and third loops that are crucial for the heterospecific follicle-stimulating hormone activity of equid luteinizing hormone/choriogonadotropin

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Identification of amino-acids in the α-subunit first and third loops that are crucial for the heterospecific follicle-stimulating hormone activity of equid luteinizing hormone/choriogonadotropin

M. Chopineau, N. Martinat, J. F. Gibrat, C. Galet, F. Lecompte, F. Foulon-Gauze, C. Pourchet, F. Guillou and Y. Combarnous

European journal of endocrinology, Vol.150(6), pp.877-884

06/01/2004

DOI: 10.1530/eje.0.1500877

PMID: 15191359

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Abstract

Objective To identify amino-acids in the alpha-subunit important for expression of heterospecific FSH activity of horse (e) LH/choriogonadotropin (CG) (eLH) and donkey (dk) LH/CG (dkLH) (FSH/LH ratio ten times higher for eLH than for dkLH); this FSH activity absolutely requires an equid (donkey or horse) alpha-subunit combined with an equid beta-LH subunit. Design Chimeric alpha-subunits possessing the first 63 amino-acids of the porcine (p) and the last 33 amino-acids of the donkey alpha-subunit (alphap-dk) and the inverse (alphadk-p) were constructed. Porcine-specific amino-acids were introduced by mutagenesis in donkey alpha-subunit at positions 70, 85, 89, 93 and 96 (alphadk5xmut), 18 (alphadkK18E) or 78 (alphadkI78A). Methods These different alpha-subunits were co-transfected in COS-7 cells with beta-eLH, beta-dkLH and beta-eFSH. The LH and FSH bioactivities of the dimers were then assessed in two heterologous in vitro bioassays. Results alphap-dk or alphadk-p exhibited FSH activity when co-expressed with beta-eLH but not with beta-dkLH. alphadkK18E or alphadkI78A gave hybrids with no FSH activity and important LH activity when expressed with beta-dkLH. alphadkI78A/betaeLH displayed an FSH/LH ratio as low as that of dkLH. However, mutation at 78 in alpha-dk had no effect on FSH bioactivity when co-expressed with beta-eFSH. Conclusions Amino-acids present in both the first two-thirds and the last third of the alpha-subunit of equid LHs are involved in their heterologous biospecificity. Ile alpha78 exerts as strong an influence on it as the beta102-103 residues. By contrast, this residue plays no role in the FSH specificity of eFSH.

Details

Title: Subtitle: Identification of amino-acids in the α-subunit first and third loops that are crucial for the heterospecific follicle-stimulating hormone activity of equid luteinizing hormone/choriogonadotropin
Creators: M. Chopineau - Centre National de la Recherche Scientifique
N. Martinat - Physiol. Reprod. des Comportements, UMR INRA-CNRS 6073, France
J. F. Gibrat - Mathématiques et Informatique Appliquées du Génome à l'Environnement
C. Galet - Centre National de la Recherche Scientifique
F. Lecompte - Physiologie de la Reproduction et des Comportements
F. Foulon-Gauze - Physiologie de la Reproduction et des Comportements
C. Pourchet - Centre National de la Recherche Scientifique
F. Guillou - Physiologie de la Reproduction et des Comportements
Y. Combarnous - Physiologie de la Reproduction et des Comportements
Resource Type: Journal article
Publication Details: European journal of endocrinology, Vol.150(6), pp.877-884
DOI: 10.1530/eje.0.1500877
PMID: 15191359
NLM abbreviation: Eur J Endocrinol
ISSN: 0804-4643
eISSN: 1479-683X
Number of pages: 8
Language: English
Date published: 06/01/2004
Academic Unit: Injury Prevention Research Center; University of Iowa Health Care
Record Identifier: 9985137927402771

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