The present invention is directed to 5' regulatory regions of two Arabidopsis seed-specific genes, AtS1 and AtS3. The 5' regulatory regions, or parts thereof, when operably linked to either the coding sequence of a heterologous gene or a sequence complementary to a native plant gene, direct expression of the coding sequence or complementary sequence in a plant seed. The regulatory regions are useful in expression cassettes and expression vectors for the transformation of plants. Also provided are methods of modulating the levels of a heterologous gene such as a fatty acid synthesis or lipid metabolism gene by transforming a plant with the subject expression cassettes and expression vectors.