ALEX II Flashcards
Protein processing
Specific proteolytic cleavage
Specificity driven by specific protein gene expression
Translational control
Translation of stable mRNA or unstable RNA, rate of translation, mRNA stable but not translated until required
e.g. mTor Kinase - controls when particular mRNA is translated
e.g. iron regulatory protein (IRP)
iron regulatory element forms secondary structure - prevents ribosome binding – no initation, when iron levle increases, IRP CANNOT bind to IRE –> translation
Post transcriptional control
mRNA stability
e. g. RBCs
- mRNAs translated by ribosomes is from progenitor cell - RNA has to be stable
mRNA translatability
mRNA stability
Aspergillus nidulans:
areA gene - positively acting transcriptional regulator
activates genes in absence of ammonium and turns them on
Presence of ammonium: transcript halflife =10mins, chew off As
Absence of ammonium: transcript half life = 40 mins
Homothallic:
HO: strains can mate with themselves, with HO - can switch mating type
Heterothallic
ho: strains msut mate with opposite mating type
HO > ho
swi5
Important for mating type switching
Overexpress SWI5
Mother and daughter both have HO
Ash1
OPPOSITE TO SWI5
Deletion of ash1: both have HO
Overexpression: neither have HO
Drosophila Sex determination
Female: 2X for every autosome - turn on splicing of sex lethal locus –> transformer locus –>female development/behaviour
DNA methylation
CpG doublets
1.De novo methylase - generally methylated on both strands
opposite = demethylase
2. maintenancy methylase
C.albicans
White state: EFG1 represses WOR2
Opaque state: WOR2 and WOR1 mutually expressing each other, wor1 is slef regulatory –> CZF1 –> blocks EFG1 –> no white phenotype
Epigenetic X chromosome inactivation
inherited
DNA methylation
De novo - doesn’t have methyl
maintenance - methylation pattern retained when cell divides
Prions
Proteins
DNA binding proteins
Further away in eukaryotes than bacteria, upstream/downstream or in introns
Insulator
Blocks transcription
Transcription factor already bound
Enhancers acting in Trans
Odorant receptors: transmembrane proteins in nasal passages that detect diff chemicals
Each cell has its own pattern of odoront receptor (1 gene - 1 odorant chemical)
H enhances activates ONE gene in cis or trans
DNA binding measuring
In vitro: mobility shift assay, footprinting, oligonucleotide selection, affinity purification
In vivo: ChIP: DNA protein interactions
In silico: Computer algorithims, compare sequences to identify conserved binding sites across orthologous genes/closely related species
ChIP:
in vivo
Light up spots for DNA fragments or sequence
Anything you have an antibody for
Epitope tag
Transcription factor
DNA binding domain
Dimerisation domain
Nuclear localisation domain
Interaction domain - modulate activation or repression
DNA binding motifs
C2H2 - Zn finger, work in multiples, interact with major groove
Helix-turn helix: 3 helicies e.g. C1 repressor
Leucine: 2 domains interact
Helix-loop helix: Interaction
