Control of Gene Expression in Molecular Mechanisms of Disease

Nucleus

Site where transcription occurs in eukaryotic cells.

Chromatin

Tightly packed DNA and protein complex in the nucleus.

Nucleolus

Region in nucleus where ribosomal RNA is synthesized.

Nuclear Envelope

Double membrane surrounding the nucleus, continuous with ER.

Nuclear Pore Complex (NPC)

Gateway for RNA and proteins across nuclear envelope.

Nucleoporins

Proteins composing the nuclear pore complex.

Nuclear Localization Signal (NLS)

Amino acid sequence directing proteins into the nucleus.

Nuclear Export Signal (NES)

Sequence that facilitates protein export from the nucleus.

Importins

Receptors that transport proteins into the nucleus.

Exportins

Transport receptors that ferry proteins out of the nucleus.

mRNA Export

Transport of mature mRNA as ribonucleoproteins.

Transcriptional State

Expression level of genes in a cell type.

Transcription Factors (TF)

Proteins that regulate transcription of specific genes.

General Transcription Factors

Bind to core promoter sites, assist RNA Pol.

Activators

Transcription factors that stimulate gene transcription.

Repressors

Transcription factors that inhibit gene transcription.

DNA-binding Domain

Region of TF that interacts with specific DNA sequences.

Zinc Fingers

DNA-binding motif using zinc ions for stability.

Helix-Loop-Helix (HLH)

Motif with two alpha helices separated by a loop.

Leucine Zipper

Dimerization motif with leucine every seventh amino acid.

Response Elements

DNA sequences where transcription factors bind.

Proximal Promoter Elements

Regulatory sequences near the transcription start site.

Distal Promoter Elements

Regulatory sequences located far from the promoter.

Enhancer Sites

Regions that increase transcription from a distance.

Co-activators

Proteins that enhance gene expression without binding DNA.

Histone Acetyltransferases (HATs)

Enzymes that add acetyl groups to histones.

Chromatin Relaxation

Process that makes DNA more accessible for transcription.

Mediator Complex

Multi-subunit protein complex essential for transcription.

SWI/SNF Complex

Chromatin remodeling complex that increases transcription accessibility.

Acetyl Group

Reduces histone positive charge, enhancing DNA accessibility.

Chromatin Remodeling Complexes

Facilitate access to DNA for transcription machinery.

CBP

Coactivator that acetylates histones for transcription.

SWI/SNF

Coactivator that remodels chromatin structure.

mRNA Processing

Modifications required for mRNA to exit nucleus.

snRNPs

Small nuclear ribonucleoproteins involved in splicing.

SR Proteins

Enhance splice site activation by binding ESEs.

hnRNP

Repress splice sites by binding to ESSs.

Exon/Intron Splicing Enhancers

Sequences that promote splicing activation.

Exon/Intron Splicing Silencers

Sequences that inhibit splicing activation.

Translation Initiation

First step in protein synthesis from mRNA.

mRNA Localization

Targeting mRNAs to specific cellular locations.

mRNA Stability

Determines how long mRNA persists in cytoplasm.

5' and 3' UTRs

Regulatory regions influencing mRNA translation.

eIF2

Initiation factor phosphorylated to inhibit translation.

Ferritin

Protein that sequesters iron in high levels.

Iron Regulatory Protein (IRP)

Regulates ferritin mRNA translation based on iron levels.

Poly(A) Tail

Length affects mRNA stability and degradation rate.

Deadenylase

Enzyme that shortens the poly(A) tail.

AU-rich Elements (AREs)

Sequences that destabilize mRNA and promote degradation.

MicroRNAs (miRNAs)

Regulate gene expression by targeting mRNA 3' UTR.

Small Interfering RNAs (siRNAs)

Inhibit gene expression by degrading specific mRNAs.

RNA Interference (RNAi)

Mechanism by which RNA molecules inhibit gene expression.

Proteasomes

Cellular complexes that degrade unneeded proteins.

Ubiquitin Ligases

Attach ubiquitin to proteins for degradation.

Polyubiquitination

Process of adding multiple ubiquitin molecules to proteins.

P-bodies

Cytoplasmic granules where mRNA degradation occurs.