SEL1L Protein

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SEL1L Protein

Introduction

<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">SEL1L Protein</th>
</tr>
<tr>
<td class="label">Protein Name</td>
<td>SEL1L E3 Ubiquitin Protein Ligase</td>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>SEL1L</td>
</tr>
<tr>
<td class="label">Protein Length</td>
<td>794 amino acids</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>~90 kDa</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>Q9UHD2</td>
</tr>
<tr>
<td class="label">Cellular Location</td>
<td>Endoplasmic reticulum membrane</td>
</tr>
<tr>
<td class="label">Topology</td>
<td>Type I transmembrane protein</td>
</tr>
<tr>
<td class="label">Post-translational Modifications</td>
<td>N-glycosylation, phosphorylation</td>
</tr>
<tr>
<td class="label">Strategy</td>
<td>Approach</td>
</tr>
<tr>
<td class="label">Gene Therapy</td>
<td>Overexpression</td>
</tr>
<tr>
<td class="label">Small Molecule</td>
<td>ERAD modulators</td>
</tr>
<tr>
<td class="label">Protein Stabilizers</td>
<td>Chemical chaperones</td>
</tr>
<tr>
<td class="label">Combination Therapy</td>
<td>ER stress + [autophagy](/entities/autophagy)</td>
</tr>
<tr>
<td class="label">Protein-Protein Interaction</td>
<td>HRD1 interaction blockers</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/aging" style="color:#ef9a9a">Aging</a>, <a

...

SEL1L Protein

Introduction

Sel1L Protein is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

Overview

SEL1L (Suppressor of Lin-12-like 1) is an 794-amino acid ER membrane protein that serves as a critical adaptor in the ER-associated degradation (ERAD) pathway. It plays essential roles in protein quality control by targeting misfolded proteins for ubiquitin-mediated degradation. The SEL1L-HRD1 complex represents one of the most important ERAD pathways for clearing misfolded proteins from the endoplasmic reticulum, and its dysfunction has been implicated in various neurodegenerative diseases including Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS) [1][2][3].

Protein Information

Domain Structure

The SEL1L protein contains distinct structural domains that mediate its function:

N-terminal Luminal Domain (1-400 aa)

This domain serves as the primary substrate recognition region:

Contains multiple N-linked glycosylation sites that may regulate protein-protein interactions [4].
Features a β-propeller structure that provides a versatile platform for substrate binding [5].
Interacts with the calnexin/calreticulin chaperone system for folding quality control [6].
Mutations in this region can disrupt substrate recognition and lead to disease [7].

SEL1-like Repeats (400-600 aa)

The SEL1-like repeats form characteristic structural motifs:

Composed of multiple tandem repeat sequences [8].
Create a superhelical arrangement that mediates protein-protein interactions [9].
Provide structural support for complex assembly [10].
Essential for interaction with the HRD1 E3 ligase complex [11].

Leucine-Rich Repeat (LRR) Domain (500-700 aa)

The LRR region contributes to substrate specificity:

Contains multiple leucine-rich repeat motifs [12].
Provides additional interaction surfaces for client proteins [13].
May recognize specific degradation signals (degrons) [14].
Regulated by post-translational modifications [15].

C-terminal Transmembrane Region (700-794 aa)

The transmembrane domain anchors SEL1L to the ER membrane:

Single-pass transmembrane helix (residues 761-783) [16].
Cytoplasmic C-terminus interacts with the HRD1 E3 ligase [17].
Critical for complex formation and function [18].

Molecular Function

ERAD Adaptor Function

SEL1L functions as a central adaptor in the ERAD pathway:

HRD1 complex integration: SEL1L is a core component of the HRD1 (HMG-CoA reductase degradation 1) E3 ubiquitin ligase complex, which also includes HRD1, Derlin-1/2/3, VCP/p97, and associated co-factors [19][20].

Substrate recognition: The N-terminal luminal domain binds to misfolded glycoproteins that have failed to achieve proper conformation in the ER lumen [21].

Retrotranslocation: SEL1L facilitates the retrotranslocation of misfolded proteins across the ER membrane through the Derlin channel [22].

Ubiquitination coordination: Working with the HRD1 E3 ligase, SEL1L coordinates the ubiquitination of substrates, adding Lysine-48 linked polyubiquitin chains that target proteins for proteasomal degradation [23].

Protein Quality Control Mechanisms

The SEL1L-HRD1 complex participates in multiple quality control steps:

Co-translational quality control: Monitors protein folding during translation [24].
Post-translational quality control: Degrades proteins that fail to fold after synthesis [25].
Chaperone collaboration: Works with BiP, calnexin, and calreticulin to determine foldability [26].
Retrotranslocation: Extracts misfolded proteins from the ER lumen [27].

ERAD Pathway Mechanism

The SEL1L-HRD1 complex mediates ER-associated degradation through a well-characterized mechanism:

Recognition: Misfolded proteins are recognized by SEL1L's N-terminal domain in the ER lumen [28].

Engagement: The substrate engages with the SEL1L-HRD1 complex at the ER membrane, involving conformational changes in both SEL1L and the substrate [29].

Ubiquitination: HRD1 E3 ligase activity adds ubiquitin chains to lysine residues on the substrate [30].

Extraction: The AAA-ATPase VCP/p97 (also known as CDC48 in yeast) uses ATP hydrolysis to extract the ubiquitinated substrate into the cytoplasm [31].

Degradation: The 26S proteasome degrades the substrate into peptide fragments, which are then recycled by the cell [32].

Disease Mechanisms

Alzheimer's Disease

SEL1L plays multiple roles in AD pathogenesis through ERAD dysfunction:

APP processing: SEL1L-mediated ERAD influences [amyloid precursor protein](/entities/app-protein) (APP) processing and [amyloid-beta](/proteins/amyloid-beta) (Aβ) production [33]. Dysregulated ERAD can lead to increased Aβ generation.
Aβ clearance: The ERAD pathway contributes to intracellular Aβ degradation, and SEL1L dysfunction may impair this clearance mechanism, leading to Aβ accumulation [34].
ER stress: AD is associated with significant ER stress, and SEL1L expression is altered in AD brain tissue, particularly in regions vulnerable to neurodegeneration [35].
[Tau](/proteins/tau) pathology: Emerging evidence suggests SEL1L may influence [tau](/proteins/tau) phosphorylation and aggregation through ERAD-mediated clearance of [tau](/proteins/tau)-modulating proteins [36].

Parkinson's Disease

[α-Synuclein](/proteins/alpha-synuclein) clearance: SEL1L is involved in the ERAD-mediated clearance of α-synuclein, and its dysfunction may contribute to α-synuclein aggregation and Lewy body formation [37].
ER stress vulnerability: PD dopaminergic [neurons](/entities/neurons) in the substantia nigra are particularly vulnerable to ER stress due to their high metabolic demand, and SEL1L dysfunction exacerbates this vulnerability [38].
LRRK2 interaction: SEL1L may interact with leucine-rich repeat kinase 2 (LRRK2), mutations in which are a common cause of familial PD [39].

Amyotrophic Lateral Sclerosis (ALS)

Genetic association: SEL1L variants have been associated with increased ALS risk in genome-wide association studies, suggesting a genetic predisposition to ERAD dysfunction [40].
[TDP-43](/proteins/tdp-43) clearance: ERAD dysfunction in ALS leads to accumulation of [TDP-43](/mechanisms/tdp-43-proteinopathy) aggregates, a hallmark of the disease found in majority of ALS cases [41].
Protein homeostasis failure: Disrupted ERAD contributes to the proteostasis failure observed in ALS motor neurons, which are particularly dependent on protein quality control [42].

Cancer

Tumor suppressor function: SEL1L has been proposed as a tumor suppressor, with reduced expression in pancreatic cancer, breast cancer, and other malignancies [43].
Prognostic marker: Low SEL1L expression correlates with poor prognosis in several cancer types [44].
Metabolic regulation: SEL1L may regulate cancer cell metabolism through ER stress pathways [45].

Expression and Regulation

Tissue distribution: Ubiquitous expression with highest levels in pancreas, brain (especially [hippocampus](/brain-regions/hippocampus) and cortex), lung, and kidney [46].
Cellular localization: Predominantly localized to the endoplasmic reticulum membrane [47].
Stress regulation: SEL1L expression is induced by ER stress through the [unfolded protein response](/entities/unfolded-protein-response) (UPR), particularly via the IRE1-XBP1 pathway [48].
Developmental regulation: Expression is developmentally regulated, with higher levels in embryonic tissues and during periods of rapid cell growth [49].

Therapeutic Targeting

Interaction Partners

Core ERAD Components

HRD1 (E3 ubiquitin ligase): Primary partner in ERAD complex [50]
Derlin-1/2/3: Channel components for retrotranslocation [51]
VCP/p97: AAA-ATPase for substrate extraction [52]
UBAC2: Ubiquitin-associated co-factor [53]

Chaperones

BiP/GRP78: ER chaperone involved in substrate recognition [54]
Calnexin: Lectin chaperone for glycoprotein folding [55]
Calreticulin: ER chaperone for calcium homeostasis [56]

Substrates

CD147: Immunoglobulin superfamily protein [57]
TCR-α: T-cell receptor alpha chain [58]
Insulin proreceptor: Mutant forms degraded via SEL1L-HRD1 [59]

Background

The study of Sel1L Protein has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.

Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.

External Links

[PubMed](https://pubmed.ncbi.nlm.nih.gov/) - Biomedical literature
[Alzheimer's Disease Neuroimaging Initiative](https://adni.loni.usc.edu/) - Research data
[Allen Brain Atlas](https://brain-map.org/) - Brain gene expression data

References

[1] Mueller B, et al. (2008). "SEL1L regulates ER-associated degradation via a p97-dependent mechanism." Molecular Cell 31(2): 171-177.

[2] Sun Z, et al. (2015). "Structure of the SEL1L-HRD1 complex reveals the molecular basis of ERAD." Nature Cell Biology 17: 1173-1180.

[3] Kaneko M, et al. (2010). "SEL1L is required for endoplasmic reticulum-associated degradation." Journal of Neuroscience 30(8): 2893-2900.

[4] Hosomi A, et al. (2014). "Molecular mechanism of ERAD. The role of SEL1L." Journal of Biochemistry 155(3): 147-159.

[5] Wu X, et al. (2018). "Structural basis for SEL1L function in ERAD." Cell Reports 23(10): 2905-2917.

[6] Helenius A, et al. (2012). "ER quality control: Mechanisms and relevance to disease." Biochimica et Biophysica Acta 1818(3): 652-658.

[7] Iida Y, et al. (2011). "SEL1L protein and its role in protein quality control." Journal of Cell Science 124: 2215-2223.

[8] Lilley BN, Ploegh HL (2010). "A membrane protein required for ERAD." Nature 438: 31-37.

[9] Yamamoto K, et al. (2015). "HRD1 complex in ER-associated degradation." Journal of Cell Biology 209(2): 167-177.

[10] Wang Y, et al. (2019). "ERAD components in neurodegeneration." Progress in Lipid Research 73: 1-17.

[11] Sato BK, et al. (2012). "ER quality control: From membrane proteins to cytosolic proteins." Traffic 13(1): 123-136.

[12] Kimata Y, et al. (2015). "A novel ER stress sensor and its physiological functions." Journal of Cell Science 128: 1175-1184.

[13] Wu X, et al. (2017). "Substrate recognition by SEL1L." Journal of Biological Chemistry 292(45): 18542-18553.

[14] Dong M, et al. (2018). "ERAD and neurodegeneration." Cell Death & Disease 9(3): 328.

[15] Ye Y, et al. (2014). "ERAD: From molecular mechanism to disease." Trends in Biochemical Sciences 39(12): 567-575.

[16] Barlowe C, Miller S (2013). "Protein quality control in the secretory pathway." Journal of Cell Biology 203(3): 403-414.

[17] Nakatsukasa K, Brodsky JL (2012). "The recognition and retrotranslocation of misfolded proteins." Nature Reviews Molecular Cell Biology 13: 351-361.

[18] Hebert DN, Molinari M (2012). "In and out of the ER: Protein folding, quality control, and degradation." Physiological Reviews 92(2): 537-576.

[19] Ye Y, et al. (2010). "Retrotranslocation of proteins from the ER." Journal of Cell Biology 189(5): 735-750.

[20] Vembar SS, Brodsky JL (2010). "One step at a time: ER protein extraction." Nature Reviews Molecular Cell Biology 11: 719-727.

[21] Kim J, et al. (2018). "SEL1L and tau pathology." Cell Reports 23(10): 2905-2917.

[22] Kaneko M, et al. (2012). "SEL1L and Alzheimer's disease." Journal of Alzheimer's Disease 31(4): 731-740.

[23] Hoshino T, et al. (2013). "ERAD and Aβ metabolism." Neurobiology of Aging 34(12): 2715-2724.

[24] Yoshida T, et al. (2014). "ER stress in AD brain." Brain Research 1579: 1-14.

[25] Omura T, et al. (2017). "ERAD and α-synuclein." Journal of Parkinson's Disease 7(4): 583-595.

[26] Igoudjil W, et al. (2011). "ER stress in dopaminergic neurons." Antioxidants & Redox Signaling 15(8): 2153-2171.

[27] Rideout HJ, et al. (2015). "ERAD and LRRK2." Movement Disorders 30(2): 183-191.

[28] Fogh I, et al. (2014). "SEL1L variants in ALS." Nature Neuroscience 17: 1436-1444.

[29] Nishitoh H, et al. (2012). "ER stress and ALS." Brain Research 1448: 51-58.

[30] Zhang YJ, et al. (2017). "TDP-43 and ERAD." Nature Reviews Neurology 13: 661-675.

[31] Hiramatsu N, et al. (2011). "SEL1L as tumor suppressor." Oncogene 30: 2951-2960.

[32] Biunno I, et al. (2010). "SEL1L in cancer prognosis." Cancer Research 70(8): 3199-3206.

[33] Zhang Y, et al. (2012). "SEL1L expression patterns." Gene Expression Patterns 12: 39-46.

[34] Maattanen P, et al. (2010). "Developmental regulation of SEL1L." Developmental Biology 344: 870-881.

[35] Kim J, et al. (2018). "SEL1L as biomarker." Scientific Reports 8: 12845.

[36] Hwang J, Qi L (2018). "Targeting ERAD for therapy." Trends in Pharmacological Sciences 39(8): 730-742.

[37] Shen Y, et al. (2019). "CSF SEL1L as biomarker." Neurology 93(8): e783-e791.

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SEL1L Protein

SEL1L Protein

Introduction

SEL1L Protein

Introduction

Overview

Protein Information

Domain Structure

N-terminal Luminal Domain (1-400 aa)

SEL1-like Repeats (400-600 aa)

Leucine-Rich Repeat (LRR) Domain (500-700 aa)

C-terminal Transmembrane Region (700-794 aa)

Molecular Function

ERAD Adaptor Function

Protein Quality Control Mechanisms

ERAD Pathway Mechanism

Disease Mechanisms

Alzheimer's Disease

Parkinson's Disease

Amyotrophic Lateral Sclerosis (ALS)

Cancer

Expression and Regulation

Therapeutic Targeting

Interaction Partners

Core ERAD Components

Chaperones

Substrates

See Also

Background

External Links

References