HSE1 Antibody

Functional Role of HSE1 in Yeast Endosomal Sorting

HSE1 forms a complex with Vps27 to regulate ubiquitin-dependent protein sorting in yeast. This complex acts as a scaffold for ubiquitin ligases (e.g., Rsp5) and deubiquitinating enzymes (e.g., Ubp7), facilitating cargo recognition and trafficking . Key mechanisms include:

• Ubiquitin Binding: The Vps27/HSE1 complex binds ubiquitinated transmembrane proteins via ubiquitin-interacting motifs (UIMs) .

• Enzyme Recruitment: HSE1 interacts with Ubp7 to modulate deubiquitination, influencing cargo fate (degradation vs. recycling) .

• Cell Surface Receptor Regulation: HSE1 deficiency disrupts the degradation of proteins like Ste3-GFP and Gap1-GFP, leading to sorting defects .

Experimental Tools for Studying HSE1

Antibodies against epitope tags fused to HSE1 are essential for detecting and characterizing this protein. Examples include:

Table 1: Plasmid Constructs Used in HSE1 Research

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Table 2: Antibody-Based Assays in HSE1 Studies

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Key Research Findings

• Ubiquitin Peptidase Interaction: HSE1 binds Ubp7 via its SH3 domain, enhancing deubiquitinating enzyme activity by ~50% in in vitro assays .

• Mutagenesis Insights: Mutations in the HSE1 SH3 domain (e.g., W254A/W255A) abolished Ubp7 binding, confirming the domain’s role in enzyme recruitment .

• Phenotypic Defects: hse1Δ yeast strains exhibit impaired degradation of Ste3-GFP and hypersensitivity to amino acid analogs like ADCB .

Methodological Advancements

• Fluorogenic Substrate Assays: Quantified Ubp7 activity using Ub-AMC, showing HSE1 enhances substrate cleavage .

• Affinity Chromatography: GST-HSE1 fusion proteins isolated via glutathione-agarose enabled mapping of protein interactions .

Implications for Human Disease

While HSE1 is yeast-specific, homologs like Hrs in humans share functional similarities in endosomal sorting. Dysregulation of these pathways is linked to neurodegenerative diseases and cancer .

Limitations and Future Directions

Current tools rely on epitope tags rather than direct HSE1 antibodies. Future studies could develop HSE1-specific monoclonal antibodies to bypass tagging requirements.