HMGA1 proteins are quite small (~10-12 kDa) and basic molecules, and consist of three AT-hooks with the RGRP (Arg-Gly-Arg-Pro) core motif, a novel cross-linking domain located between the second and third AT-hook, and a C-terminal acidic tail characteristic for the HMG family comprising HMGA, HMGB and HMGN proteins.

It has little secondary structure in solution but assumes distinct conformations when bound to substrates such as DNA or other proteins.

HMGA1 proteins have high amounts of diverse posttranslational modifications and are located mainly in the nucleus, especially in heterochromatin, but also in mitochondria and the cytoplasm.

[8] The splice variant HMGA1c with only two AT hooks and no acidic tail is in discussion to be a real member of the HMGA family.

[10] This article incorporates text from the United States National Library of Medicine, which is in the public domain.