{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}


University press transcription factor families

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: eceptors: 2 Glucocorticoid Cys2-Cys2 Zn fingers Cys – Amino acids on right side of first finger Amino used for DNA binding, regulates DNA specificity - swapping first fingers between steroid receptors changes response element recognition response – Amnio acids on left side of second Amnio finger used for dimerization finger • 2 glucocorticoid receptor monomers glucocorticoid dimerize upon DNA binding - each monomer contacts successive major groove at response element palindromic seq Lewin Genes VII 2000 Oxford University Press TRANSCRIPTION FACTOR FAMILIES: STEROID RECEPTORS STEROID RECEPTORS • mutagenesis studies have been done mutagenesis to define functional domains to • unlike other transcription factors can’t unlike separate DNA-binding and activation • C-terminal domains used for hormone C-terminal binding and regulate receptors in variety of ways variety • removal of glucocorticoid receptor Cterm domain ---> constitutive term transcription activity - an internal negative regulator whose repression released by steroid binding released • similar to what we saw for σ 7 0 in similar bacteria: in the absence of interaction with RNAP, the N-terminal domain of σ 7 0 prevents σ 7 0 from binding DNA Lewin Genes VII 2000 Oxford University Press TRANSCRIPTION FACTOR FAMILIES: STEROID RECEPTORS STEROID RECEPTORS • • • similar to operator-repressor similar interaction, each response element for steroid hormone receptors consists of 2 half sites, thus we get receptor binding as a dimer receptor response elements for a number of response different steroid receptors have same sequence in their half sites; specificity is conferred by spacing between sites between importance of spacing between half importance sites is demonstrated by finding that changing spacing in GRE from 3 bp to 4 bp disrupts proper receptor-DNA interaction receptor-DNA OPERATOR/REPRESSOR-BINDING SITES: COOPERATIVE BINDING SITES: • • • -Repressor highest affinity for OL1 & OR1 Repressor R1 -Cooperative binding: binding at site 1 Cooperative increases repressor affinity for site 2… when OL1-2 & OR1-2 bound by repressor, PL & R1-2 PR transcription blocked • each operator contains each three 17bp repressorthree binding sites with binding partial symmetry about central base pair central central bp divides each central site into 2 half-sites, which show similarity to consensus sequence each half-site binds each one monomer in repressor dimer repressor site 1 in each operator site has a 10X greater affinity for repressor than other sites than...
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online