question: Is p100 the precursor protein molecule of the NF-kappaB transcription factor subunit p50?
answer: No, the precursor molecule for NF-kappaB p50 is p105 and not p100. Nfkb2 encodes two members of the NF-kappa B/Rel family of proteins: p52 and p100. The p100 polypeptide has been proposed to serve as a precursor of p52 (and not of p50), which corresponds to the N-terminal half of p100. NF-kappaB functions as a hetero- or homo-dimer which can be formed from five NF-kappaB subunits, NF-kappaB1 (p50 and its precursor p105), NF-kappaB2 (p52 and its precursor p100), RelA (p65), RelB and c-Rel.