Essential component of the NELF complex, a complex that negatively regulates the elongation of transcription by RNA polymerase II (PubMed:31399344). The NELF complex, which acts via an association with the DSIF complex and causes transcriptional pausing, is counteracted by the P-TEFb kinase complex (PubMed:31399344). Provides the strongest RNA binding activity of the NELF complex and may initially recruit the NELF complex to RNA (By similarity). The NELF complex is composed of NELFA, NELFB, NELFCD and NELFE (By similarity). Interacts with NELFB (PubMed:26010750). Localizes to chromatin (PubMed:31399344). Phosphorylation by the P-TEFb complex promotes its release from chromatin (PubMed:31399344). The RRM domain interacts with RNA, and is essential for NELF complex function. It is however not required for the NELF complex formation (By similarity). Phosphorylated by the P-TEFb complex at sites next to its RNA recognition motif, promoting its release from chromatin. Sumoylated. The length of the RD repeats is variable. Belongs to the RRM NELF-E family.