Effect of Additional N-Glycosylation Signal in the N-Terminal Region on Intracellular Function of the Human Gonadotropin .ALPHA.-Subunit
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Accession number;03A0491621
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| Title;Effect of Additional N-Glycosylation Signal in the N-Terminal Region on Intracellular Function of the Human Gonadotropin .ALPHA.-Subunit |
| Author;
FURUHASHI M
(Dep. Obstetrics And Gynecology, Japanese Red Cross Nagoya First Hospital, Nagoya, Jpn)
SUGANUMA N
(Toyohashi Municipal Hospital, Toyohashi, Jpn)
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Journal Title;Endocr J
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Journal Code:F0625A
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ISSN:0918-8959
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VOL.50;NO.3;PAGE.245-253(2003)
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| Figure&Table&Reference;FIG.6, REF.30 |
| Pub. Country;Japan |
| Language;English |
| Abstract;hCG, LH, FSH, and TSH are a family of heterodimeric glycoprotein hormones that contain a common .ALPHA.-subunit, but differ in their hormone-specific .BETA.-subunits. The .ALPHA.-subunit has two N-glycosylation sites at Asn52 and Asn78. To obtain more information on the relationship between the structure and function of the .ALPHA.-subunit, we introduced a novel N-glycosylation site in the N-terminal region by mutating Asp3 and Gln5 into Asn and Thr, respectively. Glycosylation mutants were expressed alone or with hCG.BETA.-subunit in Chinese hamster ovary cells. New N-linked oligosaccharides were efficiently added to the wild-type and mutant .ALPHA.-subunits lacking N-glycan at Asn52 (.ALPHA..DELTA.Asn1), Asn78 (.ALPHA..DELTA.Asn2), and both (.ALPHA..DELTA.Asn(1+2)). The new sugar chain did not affect secretion and assembly except that 1) it increased the intracellular degradation of .ALPHA..DELTA.Asn(1+2), and 2) it augmented the assembly of .ALPHA..DELTA.Asn1 with hCG.BETA.-subunit. Amino acid changes generated the attachment of O-glycosylation in free .ALPHA.-subunit but not in assembled form. These data indicate that the newly introduced N-glycosylation consensus sequence is functional, and that the N-terminal region of the .ALPHA.-subunit is flexible and can be modified without affecting the intracellular function. Furthermore, amino acid sequences in the N-terminus are involved in the O-glycosylation in free .ALPHA.-subunit. (author abst.) |
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