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NYX (nyctalopin on chromosome X), the gene mutated in congenital stationary night blindness, encodes a cell surface protein


Zeitz, Christina; Scherthan, Harry; Freier, Susanne; Feil, Silke; Suckow, Vanessa; Schweiger, Susann; Berger, Wolfgang (2003). NYX (nyctalopin on chromosome X), the gene mutated in congenital stationary night blindness, encodes a cell surface protein. Investigative Ophthalmology & Visual Science [IOVS], 44(10):4184-4191.

Abstract

PURPOSE

The complete type of X-linked congenital stationary night blindness (CSNB1) in human and mouse is caused by mutations in the NYX gene. The human NYX protein has been predicted to contain an N-terminal endoplasmic reticulum (ER) signaling sequence and a C-terminal glycosylphosphatidylinositol (GPI) anchor. In the current study, these computer predictions were verified experimentally by expression of domain-specific cDNA constructs in COS-7 and HeLa cells. Moreover, computer-based analysis of the orthologue mouse amino acid sequence did not reveal a GPI anchor, which may result in a different protein localization compared with human NYX. Therefore, the cellular localization for the mouse Nyx protein was also examined.

METHODS

A new method was established that differentially visualizes both the protein at the surface of the living cell and subsequently in intracellular compartments. The localization of the human and mouse V5-tagged wild-type and mutant NYX protein were studied.

RESULTS

Human and mouse V5-NYX proteins were dispersed in the form of speckles over the entire cell surface. Subsequent staining of the same cells after detergent extraction revealed that V5-NYX located to the ER and Golgi apparatus. Deletion of the GPI anchor domain of NYX resulted in a time-dependent loss of V5-NYX from the surface of living cells and accumulation of this truncated protein in the ER and Golgi apparatus. Deletion of the ER signal sequence in Nyx delocalized the intracellular V5-Nyx protein and caused its dispersion in the cytosol. Furthermore, mutations introduced in the leucine-rich repeat (LRR)-region, which has been described as a pathogenic variant of NYX, had no effect on subcellular localization of the protein.

CONCLUSIONS

These data provide evidence that human and mouse nyctalopin are membrane-bound extracellular proteins and are functionally conserved.

Abstract

PURPOSE

The complete type of X-linked congenital stationary night blindness (CSNB1) in human and mouse is caused by mutations in the NYX gene. The human NYX protein has been predicted to contain an N-terminal endoplasmic reticulum (ER) signaling sequence and a C-terminal glycosylphosphatidylinositol (GPI) anchor. In the current study, these computer predictions were verified experimentally by expression of domain-specific cDNA constructs in COS-7 and HeLa cells. Moreover, computer-based analysis of the orthologue mouse amino acid sequence did not reveal a GPI anchor, which may result in a different protein localization compared with human NYX. Therefore, the cellular localization for the mouse Nyx protein was also examined.

METHODS

A new method was established that differentially visualizes both the protein at the surface of the living cell and subsequently in intracellular compartments. The localization of the human and mouse V5-tagged wild-type and mutant NYX protein were studied.

RESULTS

Human and mouse V5-NYX proteins were dispersed in the form of speckles over the entire cell surface. Subsequent staining of the same cells after detergent extraction revealed that V5-NYX located to the ER and Golgi apparatus. Deletion of the GPI anchor domain of NYX resulted in a time-dependent loss of V5-NYX from the surface of living cells and accumulation of this truncated protein in the ER and Golgi apparatus. Deletion of the ER signal sequence in Nyx delocalized the intracellular V5-Nyx protein and caused its dispersion in the cytosol. Furthermore, mutations introduced in the leucine-rich repeat (LRR)-region, which has been described as a pathogenic variant of NYX, had no effect on subcellular localization of the protein.

CONCLUSIONS

These data provide evidence that human and mouse nyctalopin are membrane-bound extracellular proteins and are functionally conserved.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Institute of Medical Genetics
04 Faculty of Medicine > Institute of Medical Molecular Genetics
Dewey Decimal Classification:570 Life sciences; biology
610 Medicine & health
Scopus Subject Areas:Health Sciences > Ophthalmology
Life Sciences > Sensory Systems
Life Sciences > Cellular and Molecular Neuroscience
Language:English
Date:October 2003
Deposited On:17 Jan 2023 15:26
Last Modified:30 Jan 2024 02:39
Publisher:Association for Research in Vision and Ophthalmology
ISSN:0146-0404
OA Status:Green
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1167/iovs.03-0251
PubMed ID:14507859
  • Content: Published Version
  • Language: English
  • Licence: Creative Commons: Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)