Nucleolin is a protein that in humans is encoded by the NCL gene. Nucleolin is the major nucleolar protein of growing eukaryotic cells. It is found associated with intranucleolar chromatin and pre-ribosomal particles. It induces chromatin decondensation by binding to histone H1. It is thought to play a role in pre-rRNA transcription and ribosome assembly. May play a role in the process of transcriptional elongation. Binds RNA oligonucleotides with 5'-UUAGGG-3' repeats more tightly than the telomeric single-stranded DNA 5'-TTAGGG-3' repeats. Midkine and pleiotrophin bind to cell-surface nucleolin as a low affinity receptor. This binding can inhibit HIV infection. Nucleolin at the cell surface is the receptor for the Respiratory Syncytial Virus (RSV) fusion protein. Interference with the nucleolin - RSV fusion protein interaction has been shown to be therapeutic against RSV infection in cell cultures and animal models.