|
DESCRIPTION: The Microphthalmia transcription factor (~61-64 kDa) is a transcription factor belonging to the basic helix-loop-helix leucine zipper (bHLH-ZIP) family of transcription factors that exists in a dimeric form. Identified in several different species, the protein is called Mi in the mouse and MITF in man. Mi/MITF has several functions including regulation of the development and survival of many cell types. While the primary function of Mi/MITF is transactivation of the genes involved in regulation of melanogenesis, it has also been shown to be required for osteoclast activity. Mi/MITF exists as at least three different isoforms, Mitf-A/MITF-A, Mitf-H/MITF-H, Mitf-M/MITF-M that vary in tissue expression, as splice variants, and undergoes variable phosphorylation in a MAPK regulated fashion. Mi/MITF has been shown to associate with several protein partners including CBP/p300, c-fos and PU-1 forming cytoplasmic complexes that are subsequently translocated to the nucleus. The association with p300 is regulated in a phospho-specific manner making Mi/MITF one of only two proteins to be so regulated. Mutations in MITF have been associated with Waardenburg-Syndrome Type 2.
|