We have updated our privacy policy. If you have any question, contact us at privacy@scicrunch.org. Dismiss and don't show again

Searching across hundreds of databases

Our searching services are busy right now. Your search will reload in five seconds.

Forgot Password

If you have forgotten your password you can enter your email here and get a temporary password sent to your email.

The c-IAP-1 and c-IAP-2 proteins are direct inhibitors of specific caspases.

The EMBO journal | Dec 1, 1997

The inhibitor of apoptosis (IAP) family of proteins are highly conserved through evolution. However, the mechanisms by which these proteins interfere with apoptotic cell death have been enigmatic. Recently, we showed that one of the human IAP family proteins, XIAP, can bind to and potently inhibit specific cell death proteases (caspases) that function in the distal portions of the proteolytic cascades involved in apoptosis. In this study, we investigated three of the other known members of the human IAP family, c-IAP-1, c-IAP-2 and NAIP. Similarly to XIAP, in vitro binding experiments indicated that c-IAP-1 and c-IAP-2 bound specifically to the terminal effector cell death proteases, caspases-3 and -7, but not to the proximal protease caspase-8, caspases-1 or -6. In contrast, NAIP failed to bind tightly to any of these proteases. Recombinant c-IAP-1 and c-IAP-2 also inhibited the activity of caspases-3 and -7 in vitro, with estimated Kis of <=0.1 microM, whereas NAIP did not. The BIR domain-containing region of c-IAP-1 and c-IAP-2 was sufficient for inhibition of these caspases, though proteins that retained the RING domain were somewhat more potent. Utilizing a cell-free system in which caspases were activated in cytosolic extracts by addition of cytochrome c, c-IAP-1 and c-IAP-2 inhibited both the generation of caspase activities and proteolytic processing of pro-caspase-3. Similar results were obtained in intact cells when c-IAP-1 and c-IAP-2 were overexpressed by gene transfection, and apoptosis was induced by the anticancer drug, etoposide. Cleavage of c-IAP-1 or c-IAP-2 was not observed when interacting with the caspases, implying a different mechanism from the baculovirus p35 protein, the broad spectrum suicide inactivator of caspases. Taken together, these findings suggest that c-IAP-1 and c-IAP-2 function similarly to XIAP by inhibiting the distal cell death proteases, caspases-3 and -7, whereas NAIP presumably inhibits apoptosis via other targets.

Pubmed ID: 9384571 RIS Download

Mesh terms: Antineoplastic Agents, Phytogenic | Apoptosis | Caspase 3 | Caspase 7 | Caspase 8 | Caspase 9 | Caspases | Cysteine Endopeptidases | Cysteine Proteinase Inhibitors | Cytochrome c Group | Cytosol | Enzyme Activation | Etoposide | Humans | Inhibitor of Apoptosis Proteins | Protein Binding | Protein Processing, Post-Translational | Recombinant Proteins | Signal Transduction | Ubiquitin-Protein Ligases

Research resources used in this publication

None found

Research tools detected in this publication

None found

Data used in this publication

None found

Associated grants

  • Agency: NCI NIH HHS, Id: CA-69381

BioGRID (Data, Interactions)

Publication data is provided by the National Library of Medicine ® and PubMed ®. Data is retrieved from PubMed ® on a weekly schedule. For terms and conditions see the National Library of Medicine Terms and Conditions.

We have not found any resources mentioned in this publication.