Gene regulation

two paradigms of gene regulation

housekeeping genes, conditionally expressed genes

house keeping genes

constitutively(continually) expressions, gene products are needed to run essential cell processes. Ex. gadph, actin, rRNA

Conditionally- expressed genes

inducible/ repressible, expressed in resonse to signals from inside or outside of the cell ex. cyclins, heat-shock proteins

what from pre-initiation complex(PIC)

general transcription factors and RNA polymerase II

roles of pic

1. position rna poly II at the TSS, 2. open the dsDNA to form transction bubble(open promoter complex)

each gene has unique set of cis-regulatory elements that control

transcription

cis regulatory elements

core promoter, proximal promoter, enhancer, silencer

core promoter

where GTF bind and the PIC forms

proximal promoter( KNOW this)

further upstream; other proteins bind to stabilize PIC( find tunes it)

enhancer

other dna sequences that bound by activotirs under certain conditions to increase transcription

silencer

dna sequences bound by repressor proteins decrease transcription

Anchoring of PIC by enhanceosome

increases transcription

coordination of proteins at the promoter

find tune transcription levels

enhancers bind to activator which

increases transcription levels

activators

transcription factors that bind to enhancer sequences. 2 parts: activation domain and DNA binding domain. upon receiving a signal in the cell, activator changes shape and/or localization so it is more likely to bind to its enhancer. Stabilize PIC, recreuit chromatin remodeling complex

repressor

transcription factor that bind to silencer sequences, also changes shape upon receiving cell signal, variety of strucutres/ mechansisms- physically block activors from binding, recruit machinery to silence DNA( epigenetic modifers)

resonse elements

are cis-regulatory elements bound by activators during cell signaling

combinatorial gene regulation

transcroption of gene a controlled by actiavors 1,2,3,4 ex. cell division

transcription of gene b controlled by activators 2,4,6 ex. dna repair

major way cell control gene expression is through

transcriptional control