Identification of amino-acids in the alpha-subunit first and third loops that are crucial for the heterospecific follicle-stimulating hormone activity of equid luteinizing hormone/choriogonadotropin.
Eur J Endocrinol
; 150(6): 877-84, 2004 Jun.
Article
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| MEDLINE
| ID: mdl-15191359
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.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Hormona Luteinizante
/
Hormona Folículo Estimulante
/
Aminoácidos
/
Gonadotropina Coriónica
/
Caballos
Tipo de estudio:
Diagnostic_studies
Límite:
Animals
Idioma:
En
Revista:
Eur J Endocrinol
Asunto de la revista:
ENDOCRINOLOGIA
Año:
2004
Tipo del documento:
Article
País de afiliación:
Francia