The HMG proteins are small acidic non-histone chromatin-proteins. They include:
HMG-1 and HMG-2: have multiple DNA-binding HMG boxes and bind DNA with little sequence specificity. Other members of the subfamily have a single HMG box and bind DNA with moderate specificity. These include the sex-determining factor SRY controlling testis formation, and the lymphoid enhancer binding factor LEF-1.
HMG-14 and HMG-17: bind DNA with little sequence specificity and bind nucleosome to stimulate transcription.
HMGI-type proteins: HMGI, HMGI-C and HMG-Y bind AT-rich regions of DNA. Expression is restricted to rapidly dividing tissues. HMGI-C is commonly involved in translocations at 12q14-15 in benign mesenchymal tumours. HMGI-Y has also been implicated in a range of benign tumours with translocations at translocations at 6p21.
High mobility group genes HMGA1 and HMGA-2 are found in a wide range of benign mesenchymal tumours. In benign tumours, the HMGA genes show increased expression without structural alterations. They regulate chromatin architecture and gene transcription. HMGA1 is located at 6q21, HMGA2 at 12q14-15.
References