Molekulare Zellbiologie (Fach) / - (Lektion)
In dieser Lektion befinden sich 153 Karteikarten
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- How does the actin nucleator complex Arp2/3 overcome the kinetic barrier to initiate actin polymerization? Arp2/3 structure is similar to the growing end of the filament (trimeric complex). Docking is easy. NPFs accelerate nucleation
- How do formin actin nucleators overcome the kinetic barrier to initiate actin polymerization? Formin stay attached to the "+" End and act as "processive caps"; increase in local actin concentration
- Which molecular mechanism drives Myosin movement on individual actin filaments? ATP-Hydrolysis driven structural change defines cycles of attachment/deattachment from the filament
- Which Rho GTPase and it two effectors induce lemmelipodia? Rho GTPase: Rac1 Effectors: SCAR and WAVE
- Which protein interaction mediates transient cell-cell adhesion between endothelial an white blood cells? Selectins
- Which types of channels mediate juxtracrine cell-cell communicaiton and which are their major components? GAP-junctions; Connexin and Connexon
- How is the activity of cadherins in adherens junctions regulated? Ca2+
- Specify a function for Cadherins during the embryonic development. E-Cadherin important for Blastomer compaction in 8-cell-stage
- Specify the structural groups in Proteoglycans. -Core-protein -Linker -GAG
- Which component of the APC/C is directly regulated by the spindle assembly checkpoint? What is the function of this component? SAC controls the APC/C through MCC (mitotic checkpoint complex) formation via signal from unattached kinetochore. function: inhibition of APC/C for degradation of securin, cyclin B and other mitotic substrates
- Name the cyclins that are responsible for Cdk activity during the following cell cycle stages in mammals : mitosis, G1/S transition - mitosis = Cyclin B - G1/S transition = Cyclin E - G1 = Cyclin D -S = Cyclin A
- How does the SCF control entry into S-phase? degradation of p27/kip or control of proteolysis
- How does p53 activation inhibit Cdk’s? active p53 bind to the regulatory region of p21 -> transcription -> translation -> p21 = Cdk inhibtor protein
- What is the critical substrate of separase during initiation of anaphase? Securin (inhibits separase)
- Name different molecules each that necessarily have to be imported into or exported out of the nucleus to execute their functions? Import: ribosomal proteins, histones, transcription factors, snRNPs, rRNPs Export: mRNA, tRNA, snRNA, rRNA
- What means NOR? Which genes does it comprise? And where is it localized in the genome in which number? NOR = nucleolus organizer region genes = 5.8S, 18S, 28S rRNA localized = on the short arms of the acrocentric chromosomes 13, 14,15, 21, 22
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- Which subnuclear structure is implicated in telomerase biogenesis? Which type of subnuclear body is thought to be implicated in epigenetic silencing? telomerase biogenesis = Cajal bodies epigenetic silencing = PML (promyelocytic leukaemia bodies)
- Which translocation model explains the molecular details of transport through the pore closest to reality? What type of barrier is built? selective phase model mechanical barrier (sieve-like network made from FG repeats)
- State the first identified nuclear export inhibitor and its cellular target. What is the binding mode and the chemical mechanism? Leptomycin B (LMB) --> binds irreversible at CRM1, alkylates
- Explain how negative control and positive control of differential splicing work. negative = a repressor blocks the intron positive = an activator promotes the splicing machinery
- Name examples of transcription factor binding motifs. Helix-turn-Helix, Zinc finger, Leucine zipper, Helix-loop-Helix, β-sheet, protruding peptides
- Through which one of the following mechanisms can miRNA function as a tumorsuppressor? it binds to the miRNA oncogene, inhibiting translation or inducing mRNA degradation
- What are the three main types of target proteins of signaling pathway? 1) metabolic enzyme 2) gene regulatory protein 3) cytoskeletal protein
- Which factor is the main inhibitor the NF kappa B transcription factor? What is the molecular mechanism? - IKBs (family of "inhibitors of kappa B): IKBA, IKBB, IKBE - the ankyrin repeats interact with a region in the RHD of the NF-kB proteins and by this mask their NLS and prevent nuclear translocation
- How does the large family of receptors for smell, hormones and neurotransmitters with seven transmembrane passes transmit its signal? signaling via G proteins; activation of G proteins by exchange of GDP by GTP
- Name 3-4 ways how signaling factors can be activated. 1) Contact-dependent 2) paracrine 3) synaptic 4) endocrine
- What is a method to visualize specific DNA-regions? DNA-footprinting
- WHich aminoacids transmit an import/export signal? Import: Lysin, Arginin Export: Leucin
- Name an example for a biological function of a) Nucleoli b) PML bodies Where do they play a role? a) Nucleoli sub-nuclear structure; function ribosome factory b) PML bodies belong to nuclear matrix; function e.g. epigenetic silencing
- How can the small GTPase be activated? if small GTPase = RAN, then RanGAP (RanGTPase-activating protein)
- Größe von NPCs (Kernporen) und durchschnittliche Anzahl in einer Membran. 120 nm breit und 20nm lang; Anzahl = ca. 4000
- Wo/Was bindet bei PKB/Akt an T308 S473? Die Proteinkinase B (PKB) kann mit ihrer PH-Domäne an PIP3 binden und dadurch an die Zellmembran rekrutiert werden. Dort wird sie von der Phosphoinositide-dependent Kinase-1 (PDK1) und einer weiteren Kinase an ihren Aminosäuren Serin(473) und Threonin(308) phosphoryliert und dadurch aktiviert.
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- Wird GSK3-β durch Phosphorylierung deaktiviert oder aktiviert? Deaktiviert
- Two extracellular mechanisms, that lead to membran modification: hydrophobic insertion (wedging) and scaffolding
- Name an adapter protein of LC3/ATG8 on autophagosomal membranes p62
- Which pathyway mediates sorting of endosome cargo proteins into intraluminal vesicles of late endosomes? ESCRT = endosomal sorting complex required for transport
- Properties of formin - generates linear filaments - act as processive caps
- Abbreviation of „MOMP“. Mitochondrial outer membrane permeabilization
- Process of „rapid-depolerymization of microtubulis“ , when the GTP-Cap is missing catastrophy
- How does Profilin “re-aggregate” actin-monomers? Profilin catalyzes ADP/ATP exchange
- Which class of proteins leads to formation of disulfid-bridges? Thiol-disulfide oxidoreductases
- Name three kinds of "target proteins" 1) metabolic enzyme 2) gene regulatory protein 3) cytoskeletal protein
- Which enzyme catalyzes the exchange of MAPKKK to MAPK? active RAS protein
- How does the SCF control the entry into S-Phase? degradation of p27/kip or control of proteolysis
- How does p53 activation inhibits Cdks? active p53 bind to the regulatory region of p21 -> transcription -> translation -> p21 = Cdk inhibtor protein
- What is the critical substrate of seperase during initiation on anaphase? Securin-->inhibits separase
- Name 3 factors, that can cause cancer. 1) high level of obesity 2) high level of alcohol consumption 3) low level of physical activity
- How are SNARE proteins recycled and where comes the energy therefor? - NSF (N-ethylmaleimide sensitive factor) dissociates and recycles SNAREs - ATP hydrolysis by NSF
- Name the major phosphoinositide on early endosomes. Clathrin
- Which factor mediates fission of clathrin vesicles from the donor membrane and what is it catalytic activity? - Dynamin - Catalytic activity = GTP-Hydrolyse
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