Journal article
Diversity in Tissue Expression, Substrate Binding, and SCF Complex Formation for a Lectin Family of Ubiquitin Ligases
The Journal of biological chemistry, Vol.283(19), pp.12717-12729
05/09/2008
DOI: 10.1074/jbc.M709508200
PMCID: PMC2442310
PMID: 18203720
Abstract
Post-translational modification of proteins regulates many cellular processes. Some modifications, including N-linked glycosylation, serve multiple functions. For example, the attachment of N-linked glycans to nascent proteins in the endoplasmic reticulum facilitates proper folding, whereas retention of high mannose glycans on misfolded glycoproteins serves as a signal for retrotranslocation and ubiquitin-mediated proteasomal degradation. Here we examine the substrate specificity of the only family of ubiquitin ligase subunits thought to target glycoproteins through their attached glycans. The five proteins comprising this FBA family (FBXO2, FBXO6, FBXO17, FBXO27, and FBXO44) contain a conserved G domain that mediates substrate binding. Using a variety of complementary approaches, including glycan arrays, we show that each family member has differing specificity for glycosylated substrates. Collectively, the F-box proteins in the FBA family bind high mannose and sulfated glycoproteins, with one FBA protein, FBX044, failing to bind any glycans on the tested arrays. Site-directed mutagenesis of two aromatic amino acids in the G domain demonstrated that the hydrophobic pocket created by these amino acids is necessary for high affinity glycan binding. All FBA proteins co-precipitated components of the canonical SCF complex (Skp1, Cullin1, and Rbx1), yet FBXO2 bound very little Cullin1, suggesting that FBXO2 may exist primarily as a heterodimer with Skp1. Using subunit-specific antibodies, we further demonstrate marked divergence in tissue distribution and developmental expression. These differences in substrate recognition, SCF complex formation, and tissue distribution suggest that FBA proteins play diverse roles in glycoprotein quality control.
Details
- Title: Subtitle
- Diversity in Tissue Expression, Substrate Binding, and SCF Complex Formation for a Lectin Family of Ubiquitin Ligases
- Creators
- Kevin A Glenn - Veterans Affairs Medical Center, Iowa City, Iowa 52242Rick F Nelson - Department of Otolaryngology, University of Iowa Hospitals and Clinics, Iowa City, Iowa 52242Hsiang M Wen - Department of Internal Medicine, Iowa City, Iowa 52242Adam J Mallinger - Kansas City University of Medicine and Biosciences, Kansas City, Kansas 64106Henry L Paulson - Department of Neurology, University of Michigan Health System, Ann Arbor, Michigan 48109
- Resource Type
- Journal article
- Publication Details
- The Journal of biological chemistry, Vol.283(19), pp.12717-12729
- DOI
- 10.1074/jbc.M709508200
- PMID
- 18203720
- PMCID
- PMC2442310
- NLM abbreviation
- J Biol Chem
- ISSN
- 0021-9258
- eISSN
- 1083-351X
- Publisher
- Elsevier Inc
- Grant note
- Veteran Affairs research career development award NIGMS National Institutes of Health Consortium for Functional Glycomics National Research Service Award RO1 NS47535-01 / National Institutes of Health
- Language
- English
- Date published
- 05/09/2008
- Academic Unit
- Psychiatry; General Internal Medicine; Internal Medicine
- Record Identifier
- 9984094641702771
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