Structure and functional significance of the carbohydrates of the LH/CG receptor

Rajaniemi, Hannu; Petäjä-Repo, Ulla E.; Pietilä, E. Maritta

doi:10.1016/s0303-7207(97)81879-5

Cited by 8 publications

(8 citation statements)

References 32 publications

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“…Folding is the rate‐limiting step in protein secretion. Even limited N‐glycosylation has a major role in solving complex folding problems [54,64–68]. Molecular chaperones such as calnexin and calreticulin promote correct folding of newly synthesized proteins or misfolded proteins [46,69,70] in a ‘quality control’ process.…”

Section: Discussionmentioning

confidence: 99%

“…Despite the lack of a full consensus on the matter, N‐glycosylation rather appears as a prerequisite for expressing functional receptors on the cell surface, i.e. for proper folding of the nascent receptor into a conformation allowing efficient surface expression and ligand binding, but complex carbohydrates are not required for high‐affinity ligand binding [64,68,75–81]. In this study, we show that glycosylation varies widely from one recombinant form of porcine lutropin receptor ectodomain to the other, thereby influencing the extent and quality of folding [51].…”

Section: Discussionmentioning

confidence: 99%

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Critical relationship between glycosylation of recombinant lutropin receptor ectodomain and its secretion from baculovirus‐infected insect cells

Pajot‐Augy¹,

Bozon²,

Rémy³

et al. 1999

European Journal of Biochemistry

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The lutropin receptor ectodomain overexpressed under the control of the powerful polyhedrin promoter in baculovirus-infected Sf9 insect cells, is mainly found in an inactive, intracellularly-aggregated form. It is secreted in an active form under the control of the P10 promoter, a somewhat weaker and earlier promoter, at the price of a lower production. The apparent molecular masses of the two species encoded by the same cDNA are 48 kDa and 60±68 kDa, respectively. The relationship between the extent and type of glycosylation and the extracellular targeting for the recombinant lutropin receptor ectodomains was investigated precisely with endoglycosidases, lectins of various specificities, and a glycosylation inhibitor, and tested with monoclonal and polyclonal antibodies. The results indicate that the strong polyhedrin promoter probably overwhelms the processing capacity of the ER in Sf9 cells, so that only a high-mannose precursor is expressed in large amounts. Only a minute amount of protein is secreted, which has been processed by Sf9 exoglycosidases/glycosyltransferases and bears complex/hybrid oligosaccharides. The weaker P10 promoter allows secretion of a mature and active receptor ectodomain, bearing complex glycosylation. An important O-linked glycosylation is also added post-translationally on this species. In particular, b-galactose and sialic acid residues were specifically detected in the secreted species, evidence of the induction of the corresponding glycosyltransferases or of their genes.These results suggest that Sf9 cells should eventually be engineered with chaperones and glycosyltransferases in order to improve the production of demanding glycoproteins such as the porcine lutropin ectodomain, so as to open the way to resolution of the three-dimensional structures of these receptors.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Critical relationship between glycosylation of recombinant lutropin receptor ectodomain and its secretion from baculovirus‐infected insect cells

Pajot‐Augy¹,

Bozon²,

Rémy³

et al. 1999

European Journal of Biochemistry

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“…It was demonstrated that the oligosaccharide chains were susceptible to cleavage by PNGaseF (as described above; Petäjä-Repo et al, 1991), and by neuraminidase (Rajaniemi et al, 1996). In contrast, EndoH, α-mannosidase and O-glycosidase (which cleave high mannose/hybrid N-linked sugars, mannose residues from high mannose oligosaccharides and O-linked oligosaccharides respectively) did not modify the HCG/LHR carbohydrate chains (Petäjä-Repo, 1994;Rajaniemi et al, 1996). Consequently, the HCG/LHR contains only N-linked complex oligosaccharide some of which terminate in sialic acid.…”

Section: Lh Receptormentioning

confidence: 99%

Glycosylation of G-protein-coupled receptors for hormones central to normal reproductive functioning: its occurrence and role

Wheatley

Hawtin²

1999

Human Reproduction Update

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Many hormones that are central to normal reproductive functioning mediate their physiological effects by activating a receptor which belongs to the large family of G-protein-coupled receptors (GPCR). Members of this family of receptor proteins are usually glycosylated on extracellular domains. In recent years the role of this glycosylation in cell surface expression/protein folding, ligand recognition and receptor-effector coupling has been investigated. This review summarises current knowledge of the role of glycosylation in the functioning of the receptors for gonadotrophin-releasing hormone (GnRH), luteinizing hormone/human chorionic gonadotrophin (LH/HCG), follicle stimulating hormone (FSH), oxytocin (OT) and vasopressin (AVP).

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“…Whether or not all sites are utilized has been the subject of debate, with some groups reporting carbohydrate chains at all sites (10) and others reporting use of only two or three of the consensus sites (11,12). Thus far, there is no evidence for the addition of O-linked oligosaccharide chains to the LH/hCG receptor (13). Previous reports suggest that the Asn-linked oligosaccharide chains attached to the LH/hCG receptor do not mediate the high affinity binding of hormone or ability to stimulate cyclic AMP production (8,10,13).…”

mentioning

confidence: 99%

“…Thus far, there is no evidence for the addition of O-linked oligosaccharide chains to the LH/hCG receptor (13). Previous reports suggest that the Asn-linked oligosaccharide chains attached to the LH/hCG receptor do not mediate the high affinity binding of hormone or ability to stimulate cyclic AMP production (8,10,13). The possibility that the carbohydrate chains participate in folding the immature receptor within the endoplasmic reticulum remains controversial (10,12).…”

mentioning

confidence: 99%

Retention of Glucose on Oligosaccharide Chains Linked to the LH/hCG Receptor Prevents Cell Surface Expression

Bradbury

Menon

2001

Biochemical and Biophysical Research Communications

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Structure and functional significance of the carbohydrates of the LH/CG receptor

Cited by 8 publications

References 32 publications

Critical relationship between glycosylation of recombinant lutropin receptor ectodomain and its secretion from baculovirus‐infected insect cells

Critical relationship between glycosylation of recombinant lutropin receptor ectodomain and its secretion from baculovirus‐infected insect cells

Glycosylation of G-protein-coupled receptors for hormones central to normal reproductive functioning: its occurrence and role

Retention of Glucose on Oligosaccharide Chains Linked to the LH/hCG Receptor Prevents Cell Surface Expression

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