Inositol phosphate stimulation by LH requires the entire alpha Asn56 oligosaccharide.
Inositol phosphate stimulation by LH requires the entire alpha Asn56 oligosaccharide.
复制标题
LH 刺激磷酸肌醇需要整个 α Asn56 寡糖。
DOI：
10.1016/s0303-7207(02)00297-6
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发表时间：
2003
影响因子：
4.1
通讯作者：
Bousfield,GeorgeR
中科院分区：
文献类型：
--
作者：
Nguyen,VanT;Singh,Vinod;Butnev,VladimirY;Gray,CiannM;Westfall,Suzanne;Davis,JohnS;Dias,JamesA;Bousfield,GeorgeR
Lentil lectin-bound, fucose-enriched hTSH was reported to stimulate both cAMP and inositol phosphate (IP) intracellular signalling pathways, whereas fucose-depleted hTSH stimulated only the cAMP pathway. Gonadotropins activate the cAMP pathway and in several studies higher concentrations activate the IP pathway. Since only the 10% of α subunit Asn56oligosaccharides (Asn52in humans) are fucosylated, the higher glycoprotein hormone concentrations required for IP pathway activation might be related to the abundance of competent hormone isoforms. Lentil lectin-fractionated equine (e)LHα and eFSHα preparations were combined with a truncated, des(121–149)eLHβ preparation. All four hybrid hormone preparations induced IP accumulation in porcine theca cells, suggesting that activation of the IP pathway was not dependent on fucosylation at α subunit Asn56. However, the presence of Asn56carbohydrate was necessary for increased IP accumulation. Intact, rather than Asn56-deglycosylated eLH preparations provoked a biphasic steroidogenic response by rat testis Leydig cells, suggesting that Gαistimulation was also sensitive to loss of Asn56carbohydrate. While rat granulosa cells responded to human FSH preparations in a biphasic manner, a classical sigmoidal response was obtained to eFSH and Asn56-deglycosylated eFSH, suggesting that the equine preparations did not activate Gαi. Purified oLHα Asn56oligosaccharides inhibited FSH-stimulated steroidogenesis in rat granulosa cell cultures indicating a direct role for carbohydrate in FSH action. The same carbohydrate preparation inhibited hCG-stimulated fluorescence energy transfer suggesting oligosaccharide involvement in activated LH receptor self-association.
