High Mobility Group (HMG) proteins, a group of chromosomal proteins common to all eukaryotes, bind DNA in a non-sequence-specific fashion to promote chromatin function and gene regulation, helping with transcription, replication, recombination, and DNA repair. 

    HMGB4 is HMG2-like, isoform 2, high-mobility group box 4. This gene can be found on Chromosome 1. HMGB4 contains two HMG-box regions, and is found in a variety of eukaryotic chromosomal proteins. HMGB proteins are phosphorylated to various extents. The existence of differentially modified forms increases the number of distinct HMGB protein variants in plant chromatin that may be adapted to certain functions.