Binds preferentially to the minor groove of A+T rich regions in double-stranded DNA via the second and third DBA-binding domains. It is suggested that these proteins could function in nucleosome phasing and in the 3'-end processing of mRNA transcripts. They are also involved in the transcription regulation of genes containing, or in close proximity to A+T-rich regions. In chromosomal puffs. Phosphorylated in a cell-cycle dependent manner; substantially reduced in cells that have finished proliferating and are differentiated. Phosphorylation at Ser-4 and Ser-23 results in a 10-fold weakening of DNA-binding activity and altered the mode of protein-DNA interaction. Belongs to the HMGA family.