F1Aalpha, a death receptor-binding protein homologous to the Caenorhabditis elegans sex-determining protein, FEM-1, is a caspase substrate that mediates apoptosis.
Apoptosis is an evolutionarily conserved process that is critical for tissue homeostasis and development including sex determination in essentially all multicellular organisms. Here, we report the cloning of an ankyrin repeat-containing protein, termed F1Aalpha, in a yeast two-hybrid screen using the cytoplasmic domain of Fas (CD95/APO-1) as bait. Amino acid sequence analysis indicates that F1Aalpha has extensive homology to the sex-determining protein FEM-1 of the Caenorhabditis elegans, which is required for the development of all aspects of the male phenotype. F1Aalpha associates with the cytoplasmic domains of Fas and tumor necrosis factor receptor 1, two prototype members of the "death receptor" family. The F1Aalpha protein also oligomerizes. Overexpression of F1Aalpha induces apoptosis in mammalian cells, and co-expression of Bcl-XL or the dominant negative mutants of either FADD or caspase-9 blocks this effect. Deletion analysis revealed the center region of F1Aalpha, including a cluster of five ankyrin repeats to be necessary and sufficient for maximum apoptotic activity, and the N-terminal region appears to regulate negatively this activity. Furthermore, F1Aalpha is cleaved by a caspase-3-like protease at Asp(342), and the cleavage-resistant mutant is unable to induce apoptosis upon overexpression. F1Aalpha is therefore a member of a growing family of death receptor-associated proteins that mediates apoptosis.
Chan
S L
SL
Institute of Molecular and Cell Biology, 30 Medical Drive, Singapore 117609, Republic of Singapore.
Tan
K O
KO
Zhang
L
L
Yee
K S
KS
Ronca
F
F
Chan
M Y
MY
Yu
V C
VC
D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D017209:Apoptosis; D029681:Arabidopsis Proteins; D017173:Caenorhabditis elegans; D029742:Caenorhabditis elegans Proteins; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020169:Caspases / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000737:chemistry*; D002460:Cell Line; D003001:Cloning, Molecular; D044943:Fatty Acid Desaturases / Q000378:metabolism / Q000494:pharmacology; D005260:Female; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D019151:Peptide Library; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000494:pharmacology; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism; D047888:Receptors, Tumor Necrosis Factor, Type I; D017386:Sequence Homology, Amino Acid; D014407:Tumor Cells, Cultured; D015003:Yeasts; D051020:bcl-X Protein; D019014:fas Receptor / Q000378:metabolism
D015703:Antigens, CD; D029681:Arabidopsis Proteins; C494811:BCL2L1 protein, human; D029742:Caenorhabditis elegans Proteins; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; C115306:FEM-1 protein, C elegans; C403492:FEM1B protein, human; D019151:Peptide Library; D019253:Proto-Oncogene Proteins c-bcl-2; D018124:Receptors, Tumor Necrosis Factor; D047888:Receptors, Tumor Necrosis Factor, Type I; D051020:bcl-X Protein; D019014:fas Receptor; D044943:Fatty Acid Desaturases; C084083:Fad7 protein, Arabidopsis; D020169:Caspases