A glycine-rich region in NF-kappaB p105 functions as a processing signal for the generation of the p50 subunit.
Transcription factor NF-kappaB is generally considered to be a heterodimer with two subunits, p50 and p65. The p50 subunit has been suggested to be generated from its precursor, p105, via the ubiquitin-proteasome pathway. During processing, the C-terminal portion of p105 is rapidly degraded whereas the N-terminal portion (p50) is left intact. We report here that a 23-amino-acid, glycine-rich region (GRR) in p105 functions as a processing signal for the generation of p50. A GRR-dependent endoproteolytic cleavage downstream of the GRR releases p50 from p105, and this cleavage does not require any specific downstream sequences. p50 can be generated from chimeric precursor p105N-GRR-IkappaBalpha, while the C-terminal portion (IkappaBalpha) can also be recovered, suggesting that p105 processing includes two steps: a GRR-dependent endoproteolytic cleavage and the subsequent degradation of the C-terminal portion. We have also demonstrated that the GRR can direct a similar processing event when it is inserted into a protein unrelated to the NF-kappaB family and that it is therefore an independent signal for processing.
Lin
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L
Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, New Haven, Connecticut 06520, USA.
Ghosh
S
S
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D002460:Cell Line; D002522:Chlorocebus aethiops; D003546:Cysteine Endopeptidases / Q000378:metabolism; D017931:DNA Primers; D010450:Endopeptidases; D005982:Glutathione Transferase / Q000096:biosynthesis; D005998:Glycine; D006801:Humans; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000378:metabolism; D016296:Mutagenesis; D016328:NF-kappa B / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D010957:Plasmids; D016133:Polymerase Chain Reaction; D046988:Proteasome Endopeptidase Complex; D011499:Protein Processing, Post-Translational; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D015183:Restriction Mapping; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D014162:Transfection; D014452:Ubiquitins / Q000378:metabolism
D017931:DNA Primers; D046911:Macromolecular Substances; D009097:Multienzyme Complexes; D016328:NF-kappa B; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D014452:Ubiquitins; D005982:Glutathione Transferase; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; D005998:Glycine