| Title | The {beta}104-109 sequence is essential for the production of a correctly folded ss{alpha} horse LH/CG single-chain and for its FSH activity. | | Author(s) | Galet C, Guillou F, Foulon-Gauze F, Combarnous Y, Chopineau M | | Institution | C Galet, University of Iowa, iowa City, United States. | | Source | J Endocrinol 2009 Jul 9. | | Abstract | The dual LH and FSH activity of the equine Choriogonadotropin (eLH/CG) in heterologous species makes eLH/CG a good model to study structure/function relationships of gonadotropins. In order to by-pass the problem of intracellular association of the heterodimer, a recombinant single-chain ssalphaeLH/CG was used to identify sequences in the beta subunit involved in the secretion and activities of the hormone. The C-terminal region of the beta subunit was progressively truncated. All resulting truncated single-chains were secreted in the media as detected by an anti-betapeptide antibody in reducing conditions. However using a conformation sensitive ELISA we show that the truncated single-chains were differently recognized: deletion of the last 40 aa of the beta subunit (beta109alphaeLH/CG) resulted in a 90% decrease of the recognized correctly folded hormone compared to the full-length ssalphaeLH/CG single-chain and no properly folded hormone was detected in the secretion medium when the last 46 amino-acids of the beta subunit were deleted (beta103alphaeLH/CG). We thus focused on the 6 amino-acids sequence 104-109 which belongs to the seat-belt region. Mutation of the 104-109 sequence in alanines in the full length betaalphaeLH/CG (beta104-109Alaalpha) led to a 50% decrease in the production of properly folded hormone in COS-7 as well as in alphaT3 pituitary cells. Moreover the FSH activity of this mutant was decreased by 70% whereas its LH activity remained intact. These data lead us to conclude that the 104-109 region of the beta eLH/CG subunit is essential for the secretion of a fully folded betaalphaeLH/CG and for its FSH activity but not for its LH activity. | | Language | ENG | | Pub Type(s) | JOURNAL ARTICLE
| | PubMed ID | 19589909 |
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