The term HMGN stands for High Mobility Group Nucleosome-binding. HMGN proteins are members of the broader class of High mobility group (HMG) chromosomal proteins that help in transcription, replication, recombination, and DNA repair.

Though identified more than 30 years back, little is known about the actual role of these basic proteins. There are several types of HMGN proteins; N1, N2, N3, N4 & N5. Many of these are conserved among the higher eukaryotes.

HMGNs are non-histone

Histone

In biology, histones are highly alkaline proteins found in eukaryotic cell nuclei that package and order the DNA into structural units called nucleosomes. They are the chief protein components of chromatin, acting as spools around which DNA winds, and play a role in gene regulation...

 protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

s, which associate with nucleosome

Nucleosome

Nucleosomes are the basic unit of DNA packaging in eukaryotes, consisting of a segment of DNA wound around a histone protein core. This structure is often compared to thread wrapped around a spool....

s to control transcription

Transcription (genetics)

Transcription is the process of creating a complementary RNA copy of a sequence of DNA. Both RNA and DNA are nucleic acids, which use base pairs of nucleotides as a complementary language that can be converted back and forth from DNA to RNA by the action of the correct enzymes...

 of genes

Gênes

Gênes is the name of a département of the First French Empire in present Italy, named after the city of Genoa. It was formed in 1805, when Napoleon Bonaparte occupied the Republic of Genoa. Its capital was Genoa, and it was divided in the arrondissements of Genoa, Bobbio, Novi Ligure, Tortona and...

. HMGNs control transcription

Transcription (genetics)

Transcription is the process of creating a complementary RNA copy of a sequence of DNA. Both RNA and DNA are nucleic acids, which use base pairs of nucleotides as a complementary language that can be converted back and forth from DNA to RNA by the action of the correct enzymes...

 by altering the interaction of histone H1

Histone H1

Histone H1 is one of the five main histone protein families which are components of chromatin in eukaryotic cells. Though highly conserved, it is nevertheless the most variable histone in sequence across species.- Structure :...

 with nucleosomes to maintain a decondensed chromatin

Chromatin

Chromatin is the combination of DNA and proteins that make up the contents of the nucleus of a cell. The primary functions of chromatin are; to package DNA into a smaller volume to fit in the cell, to strengthen the DNA to allow mitosis and meiosis and prevent DNA damage, and to control gene...

structure.