Transcription initiation: RNA polymerase binds to the DNA transcription promoter, The process of forming a functional transcription initiation complex. It was transcribed The rate-limiting step in the process is the first and most important step in gene expression regulation. stage.

Promoter: DNA molecule is protected by RNA polymerase and transcription regulators Recognizes and forms the transcription initiation complex.

Strong promoter: a promoter with high affinity to RNA polymerase, which The frequency and efficiency of initial transcription are both high.

Motif (-10 region promoter sequence): extremely conserved consensus sequence Column, the center of which is located approximately 10 bp upstream of the transcription start site.

Binding site (B site): RNA polymerase binds at the recognition site After clicking, move the slider to the -10 area, select the template chain and close it combine.

core promoter

Transcription start point (I site): 1 site.

Upstream control element: located in the -70~-40 region upstream of the core promoter Contains upregulation that binds to the CAP-cAMP complex and activates transcription control point.

upstream control elements

DNA footprinting method: adding RNA polymerization to the gene reaction system enzyme without adding NTP, RNA polymerase can only bind to the promoter , transcription cannot proceed. Add DNase digestion to the system DNA, a segment of DNA protected by RNA polymerase (promoter sequence) can be bound to nitrocellulose filters so that The DNA is released from the complex and its sequence is determined.

The prokaryotic promoter is about 40 bases long and contains the -10 region The conserved sequence of Pribnow box is TATAAT, -35 region The conserved sequence of the Sextama box is TTGACA, and the other two boxes There is a spacer sequence of 17±1bp between them. The conservation of the spacer sequence is conducive to Initiation of RNA polymerase. The spacing mutation approaches 17bp → an up-regulation mutation that enhances promoter function Spacing mutation away from 17bp → down-regulation mutation that weakens promoter activity

-35 sequence is the binding recognition site of rho factor in RNA polymerase holoenzyme point. The -10 region position is rich in A/T, and melting of the promoter region occurs in - In region 10, the rho factor selects the template strand and prompts the RNA The polymerase binds to the template strand.

The essential difference between strong and weak promoters is the degree of similarity with the conserved sequence -35 (TTGACA) and -10 conserved sequence (TATAAT). If the mutation causes the promoter to deviate from the standard sequence, the promoter effect is weak and the mutation appears as a down-regulation mutation; otherwise, the mutation appears as an up-regulation mutation.

Cis-element: binds to trans-acting factors and exists with target genes Nearby, the structurally conserved DNA sequence that regulates target gene transcription List. Such as: enhancer, silencer. Not directly associated with RNA polymerase Interact with other proteins to activate or organize Transcription initiation of structural genes by RNA polymerase.

Trans-acting factors: bind to cis-acting elements and regulate genes of transcription factors. Such as activator proteins, repressor proteins and ncRNA

Housekeeping genes: necessary to maintain the basic metabolic processes of cells, Expressed in different cell types and cell growth stages (constitutive expression) genes.

Luxury genes: for cell differentiation, biological development and adaptation to the environment Genes that require expression (inducible expression) due to the environment

Structural gene: Any gene that codes for protein or RNA.

Regulatory genes: genes directly involved in regulating the expression of other genes.

Eukaryotic RNA is transcribed by three RNA polymerases (Ⅰ,Ⅱ,Ⅲ)Complete

RNA polymerase is an enzyme that synthesizes RNA by polymerizing a DNA strand or RNA as a template and ribonucleoside triphosphate as a substrate through a phosphodiester bond, because it is transcribed with the genetic information of the gene DNA in the cell. Because it is related to RNA, it is also called transcriptase.

The core enzyme of RNA polymerase consists of two α subunits, one β subunit, Composed of a β’ subunit. The core enzyme relies on electrostatic forces to interact with DNA Non-specific and non-specific binding occurs, responsible for the RNA chain Transcription elongation.

The holoenzyme of RNA polymerase is composed of the core enzyme and the rho subunit. The holoenzyme relies on specific spatial structure and promoter-specific base sequences. Columns bind specifically and are responsible for the initiation of RNA transcription.

All types of RNA are transcribed by an RNA polymerase

The core enzyme of RNA polymerase contains at least 4 functional sites, namely Non-template strand binding site (β’), template strand binding site (;β subunit), double-stranded DNA unwinding site and double-stranded DNA rearrangement site point.

RNA polymerase I: located in the nucleolus before transcribing 45S-rRNA mention, which encodes 5.8S, 18S and 28SrRNA genes (Ⅰ type gene)

RNA polymerase II: located in the nucleoplasm, transcribes all coding genes mRNA and most small nuclear RNAs (snRNAs) (type II genes because)

RNA polymerase III: located in the nucleoplasm, transcribes tRNA, 5SRNA Genes and genes encoding U6 snRNA and different scRNAs (type III Gene)

1. Recognition of TATA box by TF II factor

2. TF Ⅱ B serves as a bridge factor between TF Ⅱ D and RNA polymerase. promoter, enriching high concentrations of RPB around the promoter, in TF Ⅱ F RAP30 and RAD25 in TF II H are ATPase Active DNA helicase. Form the basic transcription initiation complex

3. The kinase activity of H is responsible for the occurrence of high-frequency phosphate in type II A CTD of RPB. Acidification converts highly transcriptionally active RNA polymers into type IIO Enzymes that form the complete transcription initiation complex.

Enhancers are long-range positive regulatory cis-sites in eukaryotes. No promoter activity, but enhancer effect independent of direction and location. No gene specificity, tissue and cell specificity Specificity.

It is a method that you can use to make chromatin spread over long distances (above 1kb). are formed into a tight, condensed heterochromatin state, thereby inhibiting Regulates regions adjacent to gene transcription.

Helix-turn-helix (HTH): The concept consists of two α-helices, The α-helix at the carboxyl terminus directly binds to the base specificity of the major groove of DNA. When combined, another α-helix crosses the major groove and interacts with DNA non-specifically. combine.

Zinc finger: It is the "DNA binding domain" of the transcription factor zinc finger protein

Basic domain or leucine zipper: A basic domain refers to a highly alkaline α-helix, any factor containing a basic domain can form the same Source dimers or heterodimers. Therefore the basic domain can exist symmetrically in, combine into a short spiralized helix called a basic zipper/ Leucine zipper.

The stem-loop conformation in RNA can prevent the elongation of the complex, causing RNA polymerase pauses and dissociates from the template.

ρ factor has two structural and functional domains: 1. RNA-dependent nucleoside three Phosphatase functional domain. 2. Terminate transcription and interact directly with RNA polymerase effect. Termination efficiency versus self-nucleotide structure and following palindromic sequence related to the downstream sequence of the column.

Structure and splicing of type I introns

Structure and splicing of type II introns

Structure and splicing of spliceosome patterns Mainly occurs in the nucleus of pre-mRNA.

trans splicing

alternative splicing/alternative splicing