title: Hydrophobicity of protein determinants influences the recognition of substrates by EDEM1 and EDEM2 in human cells.
abstract: BACKGROUND
  EDEM1 and EDEM2 are crucial regulators of the endoplasmic reticulum (ER)-associated degradation (ERAD) that extracts misfolded glycoproteins from the calnexin chaperone system. The degradation of ERAD substrates involves mannose trimming of N-linked glycans; however the precise mechanism of substrate recognition and sorting to the ERAD pathway is still poorly understood. It has previously been demonstrated that EDEM1 and EDEM2 binding does not require the trimming of substrate glycans or even ERAD substrate glycosylation, thus suggesting that both chaperones probably recognize misfolded regions of aberrant proteins.
  
  
  RESULTS
  In this work, we focused on the substrate recognition by EDEM1 and EDEM2, asking whether hydrophobicity of protein determinants might be important for these interactions in human cells. In the study we used ricin, a protein toxin that utilizes the ERAD pathway in its retrotranslocation from the ER to the cytosol, and a model misfolded protein, the pancreatic isoform of human β-secretase, BACE457. Mutations in the hydrophobic regions of these proteins allowed us to obtain mutated forms with increased and decreased hydrophobicity.
  
  
  CONCLUSIONS
  Our data provide the first evidence that recognition of ERAD substrates by EDEM1 and EDEM2 might be determined by a sufficiently high hydrophobicity of protein determinants. Moreover, EDEM proteins can bind hydrophobic transmembrane regions of misfolded ERAD substrates. These data contribute to the general understanding of the regulation of ERAD in mammalian cells.
authors: Iwona
authors: I
authors: Sokołowska
authors: Ewa S
authors: ES
authors: Piłka
authors: Kirsten
authors: K
authors: Sandvig
authors: Grzegorz
authors: G
authors: Węgrzyn
authors: Monika
authors: M
authors: Słomińska-Wojewódzka
mesh_terms: D000595:Amino Acid Sequence; D053829:Amyloid Precursor Protein Secretases / Q000737:chemistry / Q000378:metabolism; D002942:Circular Dichroism; D003600:Cytosol / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism*; D006056:Golgi Apparatus; D057809:HEK293 Cells; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008565:Membrane Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D011485:Protein Binding; D011489:Protein Denaturation; D055550:Protein Stability; D012276:Ricin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity; D043323:alpha-Mannosidase / Q000378:metabolism*
chemical_list: C486654:EDEM1 protein, human; D006023:Glycoproteins; D008565:Membrane Proteins; D012276:Ricin; C497155:EDEM2 protein, human; D043323:alpha-Mannosidase; D053829:Amyloid Precursor Protein Secretases
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