Differential regulation of NF-kappaB2(p100) processing and control by amino-terminal sequences.
Proteolytic degradation of the C-terminal region of NF-(kappa)B precursors to their active DNA binding forms represents an important regulatory step in the activation of NF-(kappa)B. NF-(kappa)B2(p100) is found ubiquitously in the cytoplasm; however, the site and mechanism of processing to p52 have not previously been defined. We show by deletion mapping that processing of NF-(kappa)B2(p100) terminates at alanine 405 to generate p52 and is prevented by specific inhibitors of the multicatalytic proteinase complex. Although the C-terminal I(kappa)B-like domain of NF-(kappa)B2(p100) was constitutively phosphorylated, disruption of this phosphorylation by mutagenesis demonstrated that it was not required as a signal to mediate processing. Mutational analysis further showed that cleavage of NF-(kappa)B2 is not dependent on a specific sequence motif adjacent to alanine 405, the ankyrin repeats, or other C-terminal sequences but is directed by structural determinants amino terminal to the cleavage site, within the Rel homology domain and/or the glycine hinge region. The level of processing of NF-(kappa)B2(p100) was much lower than that of NF-(kappa)B1(p105) and differed from that of I(kappa)B-alpha, suggesting differential control of processing of NF-(kappa)B/I(kappa)B family members.
Betts
J C
JC
Department of Internal Medicine, Howard Hughes Medical Institute, University of Michigan Medical Center, Ann Arbor 48109-0650, USA.
Nabel
G J
GJ
D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D002460:Cell Line; D003593:Cytoplasm / Q000378:metabolism; D005786:Gene Expression Regulation; D013006:Growth Hormone / Q000096:biosynthesis / Q000235:genetics; D018922:HL-60 Cells; D006367:HeLa Cells; D006801:Humans; D007668:Kidney; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000096:biosynthesis*; D052003:NF-kappa B p52 Subunit; D010766:Phosphorylation; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis; D012091:Repetitive Sequences, Nucleic Acid; D014158:Transcription, Genetic; D014162:Transfection
D016328:NF-kappa B; D052003:NF-kappa B p52 Subunit; D011518:Proto-Oncogene Proteins; D013006:Growth Hormone