Molecular cloning and characterization of Bif-1. A novel Src homology 3 domain-containing protein that associates with Bax.
Bax is a proapoptotic member of the Bcl-2 protein family that commits the cell to undergo programmed cell death in response to apoptotic stimuli. To gain further insights into Bax mechanisms, we have identified a novel Bax-binding protein, termed Bif-1, by using a yeast two-hybrid cloning technique. Bif-1 is an evolutionarily conserved cytoplasmic protein that contains a predicted Src homology 3 (SH3) domain located near its C terminus but shares no significant homology with members of the Bcl-2 family. A Northern blot analysis indicates that Bif-1 is expressed in most tissues with abundant expression in heart and skeletal muscle. Bif-1 is capable of interacting with Bax as demonstrated by yeast two-hybrid, coimmunoprecipitation, and immunofluorescence studies. Induction of apoptosis in murine pre-B hematopoietic cells FL5.12 by interleukin-3 withdrawal results in increased association of Bax with Bif-1, which is accompanied by a conformational change in the Bax protein. Overexpression of Bif-1 promotes Bax conformational change, caspase activation, and apoptotic cell death in FL5.12 cells following interleukin-3 deprivation. Bif-1 thus represents a new type of regulator of Bax-mediated signaling pathways for apoptosis.
Drug Discovery Program, H. Lee Moffitt Cancer Center and Research Institute, Department of Pharmacology and Therapeutics, University of South Florida, Tampa, Florida 33612, USA.
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Cuddeback
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Yamaguchi
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Komatsu
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Miyashita
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Yamada
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Wu
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Singh
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Wang
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D017209:Apoptosis; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D002460:Cell Line; D003001:Cloning, Molecular; D018076:DNA, Complementary; D006801:Humans; D007377:Interleukin-3 / Q000378:metabolism; D008969:Molecular Sequence Data; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2; D017386:Sequence Homology, Amino Acid; D051028:bcl-2-Associated X Protein; D018909:src Homology Domains
D048868:Adaptor Proteins, Signal Transducing; C494826:BAX protein, human; D002352:Carrier Proteins; D018076:DNA, Complementary; D007377:Interleukin-3; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; C429293:SH3GLB1 protein, human; C486100:Sh3glb1 protein, mouse; D051028:bcl-2-Associated X Protein