Cited by 39Retinal Development and DisordersDrug Transport and Resistance MechanismsRetinoids in leukemia and cellular processes

Posttranslational Modifications of the Photoreceptor-Specific ABC Transporter ABCA4

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Tsybovsky, Yaroslav, Wang, Benlian, Quazi, Faraz, Molday, Robert S., Palczewski, Krzysztof·2011·Biochemistry

Abstract

ABCA4 is a photoreceptor-specific ATP-binding cassette transporter implicated in the clearance of all-trans-retinal produced in the retina during light perception. Multiple mutations in this protein have been linked to Stargardt disease and other visual disorders. Here we report the first systematic study of posttranslational modifications in native ABCA4 purified from bovine rod outer segments. Seven N-glycosylation sites were detected in exocytoplasmic domains 1 and 2 by mass spectrometry, confirming the topological model of ABCA4 proposed previously. The modifying oligosaccharides were relatively short and homogeneous, predominantly representing a high-mannose type of N-glycosylation. Five phosphorylation sites were detected in cytoplasmic domain 1, with four of them located in the linker "regulatory-like" region conserved among ABCA subfamily members. Contrary to published results, phosphorylation of ABCA4 was found to be independent of light. Using human ABCA4 mutants heterologously expressed in mammalian cells, we showed that the Stargardt disease-associated alanine mutation in the phosphorylation site at position 901 led to protein misfolding and degradation. Furthermore, replacing the S1317 phosphorylation site reduced the basal ATPase activity of ABCA4, whereas an alanine mutation in either the S1185 or T1313 phosphorylation site resulted in a significant decrease in the all-trans-retinal-stimulated ATPase activity without affecting the basal activity, protein expression, or localization. In agreement with this observation, partial dephosphorylation of native bovine ABCA4 led to reduction of both basal and stimulated ATPase activity. Thus, we present the first evidence that phosphorylation of ABCA4 can regulate its function.

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  • The overall topological model for ABCA4 is supported by glycosylation sites in both ECD domains and phosphorylation sites in CD1.

    “The overall topological model for ABCA4 is supported by multiple glycosylation sites identified in both ECD domains, whereas CD1 hosts multiple phosphorylation sites.76,521,522”

    From Chemistry of the Retinoid (Visual) Cycle (2014) · cites this paper as [521]

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Authors
Tsybovsky, Y., Wang, B., Quazi, F., Molday, R. S., & Palczewski, K.
Affiliations
  • Case Western Reserve University (US)
  • University of British Columbia (CA)
Corresponding author
Palczewski, Krzysztof
Venue
Biochemistry
Published
2011-07-08
Volume
50
Issue
32
Pages
6855-6866
ISSN
  • 0006-2960 (ISSN-L)
  • 1520-4995
OpenAlex
W2023815770
Cited by
39
References
68
Citations by year
2025: 1 · 2024: 4 · 2022: 1 · 2021: 7 · 2020: 1 · 2019: 2 · 2018: 3 · 2017: 2 · 2015: 3 · 2014: 6 · 2013: 4 · 2012: 3
FWCI
1.95
Type
journal article
Language
en
Open access
Locations
  • Biochemistry (publishedVersion)
  • PubMed (publishedVersion)
  • Europe PMC (PubMed Central) (acceptedVersion)
  • PubMed Central (acceptedVersion)
Funders
National Eye Institute (R01EY013203, R24EY021126, R01EY002422, P30EY011373, R01EY009339)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Retinal Development and Disorders
  • Health Sciences › Medicine › Oncology › Drug Transport and Resistance Mechanisms
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Retinoids in leukemia and cellular processes
Keywords
ABCA4, post-translational modification, N-glycosylation, phosphorylation, Stargardt disease, photoreceptors, rod outer segments, ATPase activity, protein misfolding, protein degradation, phosphorylation site mutation
MeSH terms
Adenosine Triphosphatases, Amino Acid Sequence, Animals, Carbohydrate Sequence, Cattle, Electrophoresis, Polyacrylamide Gel, Glycosylation, Humans, Mice, Inbred C57BL, Molecular Sequence Data, Phosphorylation, Protein Processing, Post-Translational, Rod Cell Outer Segment, ATP-Binding Cassette Transporters, Mice, Tandem Mass Spectrometry

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