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MCB 252: Exam 2
central ring
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holds NPC in the nuclear envelope; transmembrane proteins
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glycosylation
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sugar chains added post-transcriptionally to NPC nucleoporins to face cytosol; block entry by adding drugs to mess up glycosylated residues
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lectins |
plant proteins with high affinity for sugar chains; ex. WGA; if injected into cells lectins bind to the nuclear pore and block entry/exit; used to study nuclear/cytoplasm exchange
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nucleoplasm
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large 145,000 kDA protein; head/tail domains, used to study NES/NLS
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NLS/NES
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basic (positively charged: lots of lysine) AA residues that are necessary and sufficient for cellular localization
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digitonin |
detergent, causes holes in plasma membrane and makes it completely permeable=all the cytosol leaks out
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Rcc1 |
"regulator of chromosome condensation"; RanGEF, found exclusively in the nucleus of a cell
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RanBP2 |
found at the entrance of the cytoplasm, nucleoporin, binds RanGTP
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NTF2
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nuclear transport factor, shuttles RanGDP into the nucleus, fastest shuttling protein in the cells
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importin alpha
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adaptor protein, recognizes NLS on cargo
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importin beta
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imports cargo into the nucleus
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CAS |
exports importin alphas into cytoplasm
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CRM1
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main exporter of most proteins and many ribonuclear complexes; if it is killed the cell will die
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LMB |
cytotoxic drug, blocks the nuclear export of all proteins (HIV Rev), binds to pocket of CRM1 that recognizes NES
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HIV Rev
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exports unspliced HIV RNA into the cytoplasm for virion packaging, contains RNA binding domain which is also an NLS to recog. a short seq. in RNA, and an NES, lots or arginine (positively charged) to bind to DNA; NOT transporter
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heterokaryon
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fused cells with shared cytoplasm and separate nuclei, can be 2 different species
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core promoter
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regulates transcription of gene by recruiting factors that initiate transcription, common to all genes that are being transcribed by RNA pol II, not sufficient to sustain transcription because of chromosome architecture
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regulatory promoter
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where TF associate to assist in transcription
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enhancer
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increase rate of transcription by making association of RNA pol II and core promoter as stable as possible, can be anywhere
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Mediator |
protein that helps TF associate with RNA pol II
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pre-initiation complex
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RNA pol II, TFs, and Mediator
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TF |
recruit holoenzyme to DNA, has DNA binding domain to bind to specific sites, protein binding domain for interaction with pre-initiation complex to activate transcription
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H1 |
histone that sits at entry of DNA that wraps around histone, critical for 30 nm packing
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histones
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H2A&H2B dimers on the outside, more mobile; H3&H4 dimers on the inside; alpha helices interact with minor groove of DNA via arginine residues which are basic as opposed to DNAs acidity
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acetylation
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addition of acetyl group to lysine residues of histone tails in order to neutralize their positive charge and make them loosen their hold on the DNA; induce formation of euchromatin and therefore transcription; mostly H4
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lamin |
give structure to nucleus and organize heterochromatin; intermediate filaments, only one to have NLS; have long alpha helical structure that allows them to homo/heterodimer through coiled coil; leucine rich; not polar; not static
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lamin B
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present in embryos, if there is a mutation in them the cell will die, remain attached to cell membrane because their farnesyl group is not removed (has CaaX motif); 2 genes
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lamin A
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can have mutations; released as dimers; one gene--if cleaved with CaaX motif it is lamin A, if without it is lamin C which can only go through the membrane when attached to lamin A; can be in nucleoplasm=more roles than B; have farnesyl group cleave
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LBR |
lamin B receptor, interacts with heterochromatin via nucleoplasmic domain
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LAP1
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interacts with lamin B and A
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LAP2 |
interacts with lamin A
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HO gene
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endonuclease; SWI2 mutant; mutant is suppressed by mutations in H4=weakens interactions between H4 and DNA
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SW12/SNF
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part of complex that disrupts/reconfigures nucleosomes and stabilizes the binding of TFs to nucleosomal DNA; if it is mutated the complex loses function; contains an ATPase; UNWINDS DNA from nucleosome (not slide)
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SWI5
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TF that recognize binding site in heterochromatin and recruits SWI2 complex; exclusive to HO gene; has DNA binding and protein binding domains
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SAGA
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histone acetylase, recruited by SWI/SNF complex
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SBF |
transcription factor recruited by SAGA that recruits general transcription factors
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HATs |
add acetyl groups
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HDACs
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remove acetyl groups
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Gcn5 |
part of HAT complex, in yeast, transcriptional co-activator (you need it for transcription but its not sufficient alone)
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Gcn4 |
TF, binds to UAS of DNA, recruits HAT complex, has DNA binding domain and protein binding domain
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Ume6 |
recognizes URS of DNA, recruits Rpd3 HDAC via interaction with Sin3
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5' Cap
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occurs shortly after translation, 5' end recognized by cap binding complex which adds a methyl guanine cap
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RNP |
ribonucleoprotein, mRNA with associated proteins, spliced, capped, poly-A tail with poly-A binding proteins, ready for export
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CTE |
constitutive transport element, part of RNA, found in lower viruses, needs protein to carry it out of cell
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Tap |
heterodimer with P15, exports mRNA, help viral and cellular RNAs, coded for in cells, interact with nucleoporins, brought to mRNA via other RNAs that are in association
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EJCs |
exon junction complexes, deposited between exons by splicesome, recruit Tap and P15
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eIF4E |
eukaryotic initiation factor, replaces 5' cap, associates in cytoplasm after diffusion
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