ABSTRACT
Regulation of gene expression may be achieved at many different levels: overall organization of genetic material within the chromosomes and in the nucleus, transcriptional steps, mRNA metabolism, translational steps, and posttranslational events. UAS2 controls CYC1 expression independently of UAS1 and is activated by the products of the HAP2 and HAPS genes. Many yeast genes were shown to contain two or more repeats of specific UASs. The SUC2 gene contains five copies of a 7-bp UAS, which is able to promote expression of a hybrid minimal promoter, but not to confer glucose repression. The transposable element Ty can cause cell type-specific modification of the expression of adjacent genes. Expression levels observed when strong promoters are fused at a site downstream from the transcriptional start site to heterologous sequences are generally lower by a factor of ten or more than what would be expected.
