The microphthalmia transcription factor and the related helix-loop-helix zipper factors TFE-3 and TFE-C collaborate to activate the tartrate-resistant acid phosphatase promoter.

The microphthalmia transcription factor (MITF) regulates different target genes in several distinct cell types, including osteoclasts. The role of the closely related factors TFE3 and TFEC in MITF action was studied. The TFE3 and TFEC proteins were expressed in osteoclast-like cells, and both could be immunoprecipitated in a complex with MITF.

The microphthalmia transcription factor (MITF) contains two N-terminal domains required for transactivation of osteoclast target promoters and rescue of mi mutant osteoclasts.

The microphthalmia transcription factor (MITF) regulates gene expression during differentiation of several distinct cell types, including osteoclasts. A structure/function analysis was performed to determine whether transcription activation domains were important for MITF action in osteoclasts. In addition to a previously characterized acidic activation necessary for melanocyte differentiation, the analysis defined a second potential activation domain located between amino acids 140 and 185.