Transcriptional activator required for the development of normal hearing, sense of balance and kidney function. Required for the expression of SLC26A4/PDS, JAG1 and COCH in a subset of epithelial cells and the development of the endolymphatic system in the inner ear. Also required for the expression of SLC4A1/AE1, SLC4A9/AE4, ATP6V1B1 and the differentiation of intercalated cells in the epithelium of distal renal tubules. Expressed in intercalated cells of the epithelium of the distal renal tubule. Expressed in the entire otic vesicle at stage 9.5 dpc gradually restricted to the epithelium of the endolymphatic ducts at stage 16.5 dpc. Mice are deaf, impaired in their sense of balance and suffer from distal renal tubular acidosis.