Inhibitor of apoptosis proteins physically interact with and block apoptosis induced by Drosophila proteins HID and GRIM

Domagoj Vucic, William J. Kaiser, Lois K. Miller

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187 Scopus citations


Reaper (RPR), HID, and GRIM activate apoptosis in cells programmed to die during Drosophila development. We have previously shown that transient overexpression of RPR in the lepidopteran SF-21 cell line induces apoptosis and that members of the inhibitor of apoptosis (IAP) family of antiapoptotic proteins can inhibit RPR-induced apoptosis and physically interact with RPR through their BIR motifs (D.-Vucic, W. J. Kaiser, A. J. Harvey, and L. K. Miller, Proc. Natl. Acad. Sci. USA 94:10183-10188, 1997). In this study, we found that transient overexpression of HID and GRIM also induced apoptosis in the SF-21 cell line. Baculovirus and Drosophila LAPs blocked HID- and GRIM- induced apoptosis and also physically interacted with them through the Bill motifs of the LAPs. The region of sequence similarity shared by RPR, HID, and GRIM, the N-terminal 14 amino acids of each protein, was required for the induction of apoptosis by HID and its binding to IAPs. When stably overexpressed by fusion to an unrelated, nonapoptotic polypeptide, the N- terminal 37 amino acids of HID and GRIM were sufficient to induce apoptosis and confer IAP binding activity. However, GRIM was more complex than HID since the C-terminal 124 amino acids of GRIM retained apoptosis, inducing and LAP binding activity, suggesting the presence of two independent apoptotic motifs within GRIM. Coexpression of IAPs with HID stabilized HID levels and resulted in the accumulation of HID in punctate perinuclear locations which coincided with IAP localization. The physical interaction of lAPs with RPR, HID, and GRIM provides a common molecular mechanism for IAP inhibition of these Drosophila proapoptotic proteins.

Original languageEnglish (US)
Pages (from-to)3300-3309
Number of pages10
JournalMolecular and cellular biology
Issue number6
StatePublished - Jun 1998
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


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