Sm. Dharmesh et Ju. Baenziger, ESTROGEN MODULATES EXPRESSION OF THE GLYCOSYLTRANSFERASES THAT SYNTHESIZE SULFATED OLIGOSACCHARIDES ON LUTROPIN, Proceedings of the National Academy of Sciences of the United Statesof America, 90(23), 1993, pp. 11127-11131
The glycoprotein hormone lutropin (LH) bears oligosaccharides terminat
ing with the sequence SO4-4-GalNAcbeta1,4GlcNAcbeta1,2Manalpha. We hav
e determined that estrogen actively modulates expression of the GalNAc
- and sulfotransferases responsible for synthesis of sulfated oligosac
charides on LH alpha and beta subunits. Consequently, terminal glycosy
lation of LH oligosaccharides with GalNAc-4-SO4 is maintained when LH
synthesis and secretion are markedly increased, as occurs during the m
idcycle surge and following ovariectomy. Maintenance of sulfated oligo
saccharides on LH has important biologic consequences because LH circu
latory half-life as well as biologic activity at the hormone receptor
level are dramatically affected by glycosylation. To our knowledge, re
gulation of glycosyltransferase levels in response to specific stimuli
has not been observed previously, further emphasizing the biologic si
gnificance of glycosylation for expression of LH bioactivity in vivo.