Cofactor of BRCA1Cofactor of BRCA1, also known as COBRA1, is a human gene that encodes NELF-B.FunctionNELF-B is a subunit of negative elongation factor (NELF), which also includes NELF-A, either NELF-C or NELF-D, and NELF-E. NELF acts with DRB sensitivity-inducing factor, a heterodimer of SPT4 and SPT5, to cause transcriptional pausing of RNA polymerase II. COBRA1 was initially identified in a yeast two-hybrid screen using the BRCT1 domain of BRCA1 as bait.InteractionsCofactor of BRCA1 has been shown to interact with: BRCA1 C-Fos, C-jun, Estrogen receptor alpha, RDBP, and TH1L.