Structure and Tissue-Specific Expression of Members of the Mouse α-Amylase Multigene Family

Abstract

One approach to study cell differentiation is to elucidate the molecular mechanisms which govern the expression of tissue-specific genes. Such regulatory mechanisms include rates of transcription, efficiency of RNA processing, mRNA flow rates from nucleus to cytoplasm and mRNA turnover rates. The genes encoding α-amylase isoenzymes of mouse are a useful system to define which of these parameters are responsible for the accumulation of a particular gene product in highly specialized cells. The amylases of mouse have been extensively studied by biochemical and genetic means (for a review see Karn and Malacinski 1978). The a-amylase mRNA’s accumulate to very different levels in three different tissues of mouse, the pancreas, the salivary gland and the liver (Schibler et al. 1980). The a-amylase structural genes are located in two closely linked but distinct genetic loci, Amy-1 and Amy-2, on mouse chromosome 3 (Sick and Nielsen 1964, Eicher 1979). Amy-2 is expressed in the pancreas, while Amy-1 encodes the α-amylases found in the salivary gland and the liver. We have isolated the two a-amylase genes Amy-2^a and Amy-1^a and the various mRNA products using recombinant DNA technology and have studied their sequence organization (Hagenbüchle et al. 1980, 1981, Tosi et al. 1981, Young et al. 1981, Schibler et al. 1982).