RMP (RPB5-mediating protein), also known as C19orf2, NNX3 or URI, is a 534 amino acid protein that localizes to the nucleus and belongs to the RNA polymerase II subunit 5-mediating protein family. Expressed ubiquitously, RMP functions as a component of the multi-protein URI complex and is thought to play a role in protein scaffolding that may be involved in transcription and ubiquitination. Multiple isoforms of RMP exist due to alternative splicing events. The gene encoding RMP maps to human chromosome 19, which consists of over 63 million bases, houses approximately 1,400 genes and is recognized for having the greatest gene density of the human chromosomes.