Role of Transcriptional Elements in Activating Origins of Replication

Transcriptional elements found in promoters and enhancers function as components of several eukaryotic origins of replication (reviewed in DePamphilis, 1988; DePamphilis et. al., 1988). These origins consist of at least two primary components (Fig. 1). The core component (ori-core) is required for initiation of replication under all conditions, and generally is the place where DNA replication begins. Auxiliary components (ori-core) flank one or both sides of ori-core and consist of promoter or enhancer elements that facilitate the core’s activity. Unlike the core component which is required for replication under all conditions, auxiliary sequences are dispensable in some cells (e.g. fertilized mouse eggs; Martinez-Salas et. al., 1988; 1989) and under some in vitro replication conditions (Guo et. al., 1989; Chen and Kelly, 1989; Gutierrez et. al., 1990).