Many biological processes are controlled, spatially and temporally, at
the level of transcription. Thus understanding the mechanism of trans
criptional regulation of gene expression is critical in deciphering th
e molecular modes of differentiation and development of a eukaryotic c
ell. Transcriptional control is mediated largely through interactions
of regulatory transcription factors with their cognate enhancer elemen
ts. The regulatory signals generated at enhancer elements are communic
ated to the general transcription machinery formed at the core promote
r elements of all genes. Recent observations suggest that the general
transcription machinery call also generate regulatory signals independ
ent of enhancer-generated interactions. Thus, the transcriptional regu
lation of gene expression both in time and in space, may result from a
ppropriate interfacing of independent signals generated at the core pr
omoter and at the enhancer.