The atypical N-glycosylation motif, Asn-Cys-Cys, in human GPR109A is required for normal cell surface expression and intracellular signaling
The atypical N-glycosylation motif, Asn-Cys-Cys, in human GPR109A is required for normal cell surface expression and intracellular signaling
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人 GPR109A 中的非典型 N-糖基化基序 Asn-Cys-Cys 是正常细胞表面表达和细胞内信号传导所必需的
DOI：
10.1096/fj.14-267096
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
M.
中科院分区：
文献类型：
--
作者：
Yasuda;D.;Imura;Y.;Ishii;S.;Shimizu;T.;and Nakamura;M.
Asparagine-linked glycosylation (N-glycosylation) is necessary for the proper folding of secreted and membrane proteins, including GPCRs. Thus, many GPCRs possess the N-glycosylation motif Asn-X-Ser/Thr at their N-termini and/or extracellular loops. We found that human GPR109A (hGPR109A) has an N-glycosylation site at Asn17 in the N-terminal atypical motif, Asn17-Cys18-Cys19. Why does hGPR109A require the atypical motif, rather than the typical sequence? Here we show that Asn17-Cys18-Cys19 sequence of hGPR109A possesses 2 biologic roles. First, Asn17-X-Cys19 contributed to hGPR109A N-glycosylation by acting as an atypical motif. This modification is required for the normal surface expression of hGPR109A, as evidenced by the reduced surface expression of the nonglycosylated mutants, hGPR109A/N17A, and the finding that hGPR109A/C19S and hGPR109A/C19T, which are N-glycosylated at Asn17, exhibited expression similar to the wild-type receptor. Second, the X-Cys18-Cys19 dicysteine is indispensable for hGPR109A function. Substitution of Cys18 or Cys19 residue to Ala impaired Gi-mediated signaling via hGPR109A. We propose the disulfide bond formations of these residues with other Cys existed in the extracellular loops for the proper folding. Together, these results suggest that the atypical motif Asn17-Cys18-Cys19 is crucial for the normal surface trafficking and function of hGPR109A.—Yasuda, D., Imura, Y., Ishii, S., Shimizu, T., and Nakamura, M. The atypical N-glycosylation motif, Asn-Cys-Cys, in human GPR109A is required for normal cell surface expression and intracellular signaling.
