[Alternative promoters and the complexity of the mammalian transcritome]

Recent studies suggest that about half of mammalian genes contain alternative promoters. This high frequency of alternative promoters implies a crucial role in expanding the expression diversity of the mammalian genome. In the present review we describe the consequences and significance of alternative promoter usage in the formation of structural and functional variety of protein isoforms in eucariotic cells. The role of alternative promoters in formation transcript variants with diverse transcription pattern and translation efficiency; in synthesis of protein isoforms with different N-termini; in synthesis different proteins encoded by alternative open reading frames; in synthesis of protein isoforms with different, sometimes opposite biological functions; in expression of some housekeeping genes; and also in formation of variety variable domains of adhesion molecules and receptors is discussed.