HMGA1B: ProductsHMGA1B (High mobility group A1, isoform B; also HMG-Y) is a 10-11 kDa member of the HMGA family of proteins. It is ubiquitously expressed, and occurs principally in tumor and embryonic tissue. HMGA1B is a nonhistone architectural protein that binds to AT-rich DNA sequences. It participates in both gene repression and activation by changing DNA conformation, and is known to regulate miRNA as well. Human HMGA1B is 96 amino acids (aa) in length and contains three A-T hook DNA-binding domains (aa 21-31; 42-52; 67-78). It is constitutively phosphorylated, and may undergo acetylation. There are three potential splice variants. All three show the same 11 aa insertion after Pro34. In addition, one form shows an additional 56 aa substitution for aa 55-96, while a second shows a 14 aa substitution for aa 80-96. Full-length human HMGA1B shares 97% aa identity with mouse HMGA1B.