ABSTRACT
Transcription control elements specific for hepatocytes are a prerequisite for targeting the expression of heterologous proteins to the liver of transgenic ani mals. Several promoters have been used to direct expression of transgenes to liver cells, e.g. those of the albumin, the alpha 1-antitrypsin (alAT), or the antithrom bin III genes (1-11). Consistent with the fact that a 1 AT (12,13) is one of the major secreted hepatic proteins, with plasma levels ranging from 1 to 3 mg/ml, the promoter of the alA T gene might be of choice for efficient, hepatospecific expression. The alAT promoter has been extensively studied, and liver-specific (14-23), macrophage-specific (24), and negative (25) cd-acting DNA sequence elements have been determined.
