11: Tissue Architecture Flashcards
Microfilament structure
F-actin filaments; form plus and minus ends
Stability of microfilaments
Generally unstable but many different proteins bind to it to help stabilize and strengthen it
Microfilament functions
Cell movements: locomotion, phagocytosis, division, contraction, etc.
Three drugs that affect actin filaments
Phalloidin, Cytochalasin, Latrunculin
Phalloidin
Binds and stabilizes microfilaments -> used in lab attached to fluorescent proteins to visualize cell shape
Cytochalasin
Caps microfilament plus end, preventing polymerization
Latrunculin
Binds actin monomers, preventing polymerization
Microtubule structure
Alpha and beta tubulin subunits form microtubules with plus and minus end; forming long, stiff tubes with a hollow core
Microtubule function
Organization
Five drugs that affect microtubules and what theyre all three typically used for
Taxol, Colchicine, colcemid, vinblastine, vincristine: all for cancer tx
Taxol
Binds and stabilizes microtubules
Colchicine, colcemid, vinblastine, vincristine function
Bind tubulin dimers, preventing dimerization -> inability to pull chromatids apart during cell division
Structure of intermediate filaments
Lamin proteins form rope-like filaments with high tensile strength
Two things accessory proteins can do to intermediate filaments
- Cross link filaments into bundles
2. Link intermediate filaments to microtubules, actin, and cell junctions
Two types of intermediate filaments and their general function
Cytoplasmic: cell specific
Nuclear: form the nuclear lamina
Three examples and cytoplasmic filaments and where theyre located
Keratin: in epithelium
Vimentin filaments: in CT, muscles, neuroglia
Neurofilaments: in neurons
Nuclear lamina
Mesh-like structure under the nuclear envelope formed by nuclear intermediate filaments
Main protein in the ECM
Collagen
Collagen structure
Trimeric protein that forms fibers, sheets, or transmembrane structures
Collagen synthesis steps
- In ER: hydroxylation of P and K residues
- In ER: glycosylation of K residues
- In Golgi: packaged and prepared for secretion in secretory vesicles
What two cofactors are required for collagen synthesis (the hydroxylation part)?
Fe, Vitamin C
Some collagen-related symptoms of scurvy
- Decreased wound healing
- Loss of teeth
- Anemia
- Pale skin
- Sunken eyes
Four types of cell junctions
- Anchoring junctions
- Occluding junctions
- Channel-forming junctions
- Signal-relaying junctions
Three types of anchoring junctions
Adherens, desmosomes, hemidesmosomes
Anchoring junction 2 functions
- Links cells together
2. Strengthens contact between cells + ECM
Occluding junctions: one type
Tight junctions
Occluding junctions: function
Seals gap between cells -> barrier impermeable to diffusion
Channel-forming junction: one type
Gap junction
Channel-forming junction function
Link cytoplasm of adjacent cells -> allows transport
Signal relaying junction: one example
Synapse
Structure of integrins
15a + 8B subunits -> combine to form over 20 heterodimeric integrins
Types of binding done by the Ig superfamily
Homophobic and heterophilic binding
Structure differences between ICAM, VCAM, etc. and MAdCAM-1
ICAM/VCAM: variable # of Ig-like domains
MAdCAM-1: Ig-like domains + mucin-like domains
Adherens: where and what is interacting
Latera adhesion; cadheren-actin interaction
Desmosomes: where and what is interacting
Lateral adhesion; cadherens-intermediate filaments
Hemidesmosomes: location and what is interacting
Basal interactions; integrins-intermediate filament interactions
What type of cell junction is targeted in pemphigus vulgaris?
Desmosomes
What end of a cell do occludens encircle cells?
Most apical side
Two proteins involved in occluding junctions
Occludins, claudins
Protein involved in channel-forming junctions (gap junctions)
Connexin aggregates
Enzyme used to make collagen
Prolyl hydroxylase
