The insulin-like growth factor 1 (IGF-1) receptor is a substrate for gamma-secretase-mediated intramembrane proteolysis |
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Authors: | McElroy Brian Powell James C McCarthy Justin V |
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Affiliation: | Signal Transduction Laboratory, Biochemistry Department, National University of Ireland, Cork, Ireland. |
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Abstract: | Several type-1 membrane proteins undergo regulated intramembrane proteolysis resulting in the generation of biologically active protein fragments. Presenilin-dependant gamma-secretase activity is central to this event and includes amyloid precursor protein (APP), Notch and ErbB4 as substrates. Here we show that the insulin-like growth factor 1 receptor (IGF-IR) undergoes regulated intramembrane proteolysis. A metalloprotease-dependant ectodomain-shedding event generates a approximately 52 kDa IGF-IR-carboxyl terminal domain (CTD). The IGF-IR-CTD is consequentially a substrate for gamma-secretase cleavage, liberating a approximately 50 kDa intracellular domain (ICD) that can be inhibited by a specific gamma-secretase inhibitor. This study suggests that the IGF-IR is a substrate for gamma-secretase and may mediate a function independent of its role as a receptor tyrosine kinase. |
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Keywords: | APP, β-amyloid precursor protein CTD, COOH terminal domain ICD, intracellular domain IGF-IR, insulin-like growth factor 1 (IGF-1) receptor |
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