SUMMARY PARAGRAPH for FET4
Although originally identified as a low-affinity iron(II) permease (1, 3), Fet4p has since been shown to import several other transition metal ions, including copper (2, 4) and zinc (5). Copper, cobalt, and cadmium inhibit Fet4p (1, 2). Fet4p is an integral protein of the plasma membrane (3, 6). FET4 is not essential, not even in an fet3 background (1). Overexpression of FET4 improves growth under alkaline conditions (7).
Transcription of FET4 is induced by Aft1p in response to low levels of iron (3, 5, 8) or by Zap1p in response to low zinc (5, 9), but not in response to low copper (5). When the high-affinity iron permease component Fet3p is deleted, FET4 is induced by the addition of copper, zinc, cobalt, or manganese (10). It is also induced under anaerobic conditions (8, 11, 12) and repressed by Rox1p in aerobic conditions (5, 8). Rox1p attenuates the activation of FET4 by Aft1p or Zap1p (5).
Last updated: 2005-08-08