RelA p65 (v-rel reticuloendotheliosis viral oncogene homolog A) is a 65 kDa member of the NF kappa B family of nuclear transcription factors. Dimers of p65 with the p50 subunit are the most common form of the NF kappa B transcription factor, but dimers with it or other family members can also occur. Upon activation, RelA p65 forms an heterotetramer and moves into the nucleus where it binds to specific DNA sequences. An alternatively spliced isoform that lacks amino acids (aa) 222‑231 (p65 delta ) does not bind DNA. Over the sequence used as an immunogen, human RelA p65 shares 96% and 98% aa identity with mouse and rat RelA p65, respectively. This portion includes one of eight potential ser/thr phosphorylation sites, two acetylation sites, and most of the Rel homology domain that interacts with I kappa B inhibitors.
