Required for ammonia secretion (By similarity). Also required for wild-type expression of ArfA. Expressed equally at pH 5.5 and 7.2. Part of the arfA-arfB-arfC operon. No effect of a single gene deletion on growth at pH 7.0 nor of whole-operon deletion on growth at pH 4.6, 5.5 or 7.2. No effect of whole-operon deletion on growth in macrophages. Loss of expression of ArfA. Belongs to the ArfC membrane protein family.