分子遗传学课件基因表达的调节宣讲培训.ppt

Cis-acting elements is the special DNA sequence that can affect the expression of its own gene. Features of Cis-acting elements Promoter Core promoter TATA-box, Initiator (Inr) Proximal elements of promoter CAAT-box, GC-box ,CpG islands Typical Eukaryotic Gene, with  Its Core Promoter and Proximal Control Region Sequence: TATAAAA Location: - 25 ~ - 30 bp Function: It is the binding site for TFII D, which is required for RNA polymerase binding. It controls the veracity and frequency of transcriptional initiation. TATA box Sequence: GCCAAT Location: ~ -70 bp Function: It is the binding site for CTF1 (CAAT-binding transcription factor1) and C/EBP (enhancer binding protein). CAAT box Sequence: GGGCGG Location: -30 ~ -110 bp Function: It is the binding site for a protein called Sp1. GC box CpG islands Genomic regions that contain a high frequency of CG dinucleotides. CpG islands particularly occur at or near the transcription start site of housekeeping genes. It is a DNA sequence that can determine the temporal and spatial specificities of expression and increase the promoter activity. Enhancer It is a negative regulation element. It will repress the transcription once interacted with specific proteins. Silencer Terminator A DNA sequence just downstream of the coding segment of a gene, which is recognized by RNA polymerase as a signal to stop transcription. Regulatory proteins The regulatory proteins are called transcription factors (TF). After expression, TF will interact with the cis-acting elements to activate another genes. Therefore, they are referred to as trans-acting factors. Control of Transcription Initiation In eukaryotes, most control of protein gene expression is at the level of transcription initiation, controlled by promoter (immediately upstream) and enhancers (distal from the gene). Expression from th