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122 Cards in this Set
- Front
- Back
ARP |
Actin Related Protein |
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Formins |
A nucleation protein of actin at the (-) end. Responsible for bundles. Often connected to the plasma membrane. |
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Alpha-actin |
Goes between actin filaments to form a contractile bundle which is loose and allows myosin II to enter. Form in stress fibers. |
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Fimbrin |
Goes between actin filaments to form parallel bundles which are tight and do not allow myosin II to enter.
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Profilin |
Binds to actin monomers making them available for filament addition. |
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Thymosin |
Binds to actin monomers making them unavailable for filament addition. |
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Filamin |
Cross-links with actin to form a gel that fills the lamellipodia cell projection. Filamin fills it in. |
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Myosin II |
Motor protein that moves along actin and is responsible for contraction. Most move to (+). Form bipolar filaments. |
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Myosin V |
Motor protein that carries cargo, things with suffix "somes". Moves to the (+) end. |
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Myofibrils |
Cylindrical structure that spans a muscle's length, there are several per muscle cell (muscle fiber) |
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Sacromere |
A band in the myofibril between Z disks (+) that contains a dark band of myosin II and two light side half-bands that are composed of actin |
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Titin |
The spring-like protein that pushes the Z disk away from the myocin (relaxing) |
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Tropomyosin |
Twists around actin. In it's usual binding place it allows myosin to bind
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Troponin |
Pulls tropomyosin out of its regular spot into a spot that blocks myosin. Occurs with low Ca2+ and relaxes muscles |
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Sarcoplasmic reticulum |
modified ER that surrounds each myofibril |
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T tubules |
Surround each myofibril and release some Ca2+ which binds to SR which releases a lot of Ca2+ |
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Alpha-tubulin |
One of the molecules of the tubulin heterodimer. Binds to GTP which cannot be lost or hydrolized. |
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Beta-tubulin |
One of the molecules of the tubulin heterodimer. Binds to GTP and is a GTPase. |
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MAPs (2 examples) |
Microtubule Associated Protein Stabilizes microtubule ends for growth Ex: MAP2 (longer) and tau (shorter and angled) |
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Catastrophe factors |
Destabilize microtubules by bending the ends |
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Stathmin |
Binds to tubulin subunits to block their addition to the microtubule. Becomes inactive and releases the tubulin when phosphorylated. The concentration of tubules is constant. |
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Gamma-tubulin |
A protein part of the gamma-TuRC (tubulin related complex) that nucleates/caps microtubules at the (-) end |
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Centrosome |
A MTOC (Microtubule organizing center) that is near the nucleus. Made of centrosome matrix and 50+ Gamma-TuRC. Plants and fungi don't have them |
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Centrioles
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Short modified mictrotubules that are at right angles to one another in the centrosome. Duplicate in the S-G2 phase |
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Kinesins |
Motor proteins that move to the (+) end of microtubules. Extend the ER |
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Dynesins |
Motor proteins that move to the (-) end or microtubules. Faster than kinesins. Shaped like a ring on a stalk which connects to a microtubule. Turning of the ring powers movement. Keep the Golgi near to the centrosome |
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Kinesin-1 |
Carries cargo on mictrotubules |
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Kinesin-3 |
Carries membrane-enclosed organelles on microtubules |
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Kinesin-5 |
Slides microtubules in opposite directions |
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Kinesin-13 |
A kinesin motor protein turned catastrophe factor |
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Kinesin-14 |
Moves to mictrotubule (-) end |
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Cytoplasmic intermediate filaments |
Not in all eukaryotes. Subject to mechanical stress |
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Nuclear intermediate filaments |
In all eukaryotes. On the interior of the nuclear membrane. One kind: lamins |
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Vimentin-like intermediate filaments |
Vinmentin, desmin (muscle)
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Epithelial intermediate filaments |
Keratins |
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Axonal intermediate filaments |
Neurofilament proteins |
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Plectin |
Links intermediate filaments to themselves or other fibers/structures |
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Septins |
Filaments that are non-polar, form rings and cages, recruit the actin myosin ring in cell division, and keep proteins localized |
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Adult cells that divide |
Epidermis, epithelial, bone marrow, liver, neurons |
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Cell cycle phases |
G1, S, G2, M |
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Late G1 checkpoint |
Growth factors/Mitogens signal the cell to continue. Fix DNA before replication. Implied in cancer. P53 increases P21 that inhibits G1/S and S-Cdks if there is unfixed DNA damage. Passes the checkpoint when there is no negative signal. |
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Late G2/ G2M checkpoint |
Check replicated DNA for errors (ssDNA). If there are errors then cdc25 is inhibited which then fails to activate M-Cdk. Passes the checkpoint when there is no negative signal |
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Metaphase/Anaphase checkpoint |
Check all chromosomes are attached to the spindles. M-Cdk activates cdc20 which activates APC. APC ubiqutinates securin which releases separase which initiates anaphase |
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Cyclins |
Manage the cell cycle through binding to Cdks which activate other proteins and are directed by the cyclins. Go through cycles of synthesis and degredation |
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Cdk |
Cyclin dependant kinase. Phosphorylates other proteins. Has constant concentrations |
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CAK |
Cdk-activating kinase, increases Cdks activity by phosporylating a Cdk with cyclin bound |
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G1 cyclins |
Promote start in G1 |
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G1/S cyclins |
Bind Cdks at the end of G1 Commit the cell to replication |
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S cyclins |
Bind Cdks during S phase. Needed for replication initiation |
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M cyclins |
Promote mitosis |
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Wee1 |
A kinase that adds an inhibitory phosphate to M-cyclin-Cdk. Is inhibited by active M-Cdk. Positive feedback (M-Cdk increase causes more M-Cdk to be active) |
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Cdc25 |
A phosphatase that removes the inhibitory phosphate from M-Cdk. Is inhibited in the late G2 checkpoint by incomplete replication. In a positive feedback loop and activated by M-Cdk so if one activity falls both fall. |
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p27 |
A CKI (Cyclin-Cdk Inhibitor) Binds to cyclin-Cdk and blocks its activity. A mutation could cause cancer |
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APC |
Anaphase Promoting Complex Ubiquitinates the cyclin of M-Cdk and the cyclin gets released into the proteasome because M-cyclin must be low at the metaphase/anaphase interface. Inhibited by unattached kinetochores. Ubiquitinates securin which frees separase and the chromosome separates |
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Cdc20 |
Binds to APC activating it to ubiquitinate M-Cdk. Is activated by M-Cdk. Think caterpillar and grass |
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ORC |
Origin replication complex. Caused to fire by phosphorylation by S-Cdk and does not fire twice due to the phosphate. |
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Prophase |
Chromosomes condense. Mitotic spindle forms |
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Prometaphase |
The nuclear envelope breaks down. The centrosomes align at the poles. Kinetochores attach to the mictrotubules from the closer pole for movement, not division yet. |
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Metaphase |
Chromosomes line up at the equator walked there by kinesins from one pole. The kinetochores become attached to both poles. Metaphase/anaphase checkpoint |
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Anaphase |
Chromosomes are split and moved towards the poles. Kinetochore mictrotubules shorten and the centrosomes move towards opposite membranes |
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Telophase |
The nuclear envelope reforms and chromosomes decondense. Contractile ring is developing for cytokinesis |
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Cohesins |
Hold sister chromatids together along their whole length |
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Condensins |
Help chromosome condensation |
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Astral microtubules |
Connect centrosomes to the plasma membrane. Dyneins attached to the membrane pull the centrosomes towards the membrane (anaphase movement A) |
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Kinetochore microtubules |
Connect chromosomes to the poles |
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Interpolar microtubules |
Attach to a microtuble of the opposite pole. Are walked apart by kinesins (anaphase movement B)
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Ndc80 |
Attach microtubules to the kinetochore when dephosphorylated. Are not phosphorylated when there is tension so tension leads to pulling apart of the chromatids. |
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Cytokinesis |
The actin myosin contractile ring tightens. Interphase microtubules are nucleated by the centrosomes. The ring gets smaller by disassembling of actin/myosin filaments. ER is cut in two, mitochondria are randomly distributed. |
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Cell plate |
The new cell wall that forms between two daughter cells in plants guided by a phragmoplast of overlapping microtubules |
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Somatic cells |
Divide by mitosis (2n --> 2n) |
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Germ cells |
Precursors to eggs and sperm that divide by meiosis (2n --> 1n, not a part of the cell cycle) |
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Phases of Meiosis |
G1, S, G2, Meiotic division 1, Meiotic division 2 |
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Bivalent |
Two matching pairs of sister chromatids lined up (one maternal one paternal) and held together by cross-overs. The daughters get one of the pair by random |
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Chiasma |
Cross-overs. Hold together the bivalent |
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Meiotic prophase 1 stages |
Leptotene, zygotene, pachytene, diplotene, diakinesis |
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Leptotene |
1st phase of prophase 1 Sister chromatids bundle together and form visible strands in the nucleus |
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Zygotene |
2nd phase of prophase 1 Synapsis (coming together) of homologs by assembly of the synaptonemal complex. Zygo = pairing |
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Pachytene |
3rd phase of prophase 1 A tetrad forms from the pairs of sister chromatids on either side. This is the bivalent. Chiasmata form |
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Diplotene |
4th phase of prophase 1 The synaptonemal complex degrades leaving homologs attached by just the chiasmata. How mammal eggs are kept until ovulation |
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Diakinesis |
5th phase of prophase 1/1st phase of metaphase 1 Nuclear membrane disintegrates and the metotic spindle begins to form |
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Mitogens |
Stimulate DNA replication by triggering G1-CDK and G1/S-Cdk. Signal through RTK (so do growth factors) |
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Myc |
A gene regulatory protein that activates G1-Cdk which adds inhibitory phosphates to Rb causing it to release E2F which causes transcription of G1/S and S-cyclins leading to S phase. Expression is increased by mitogen/GF binding to RTKs.
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p53 |
Phosphorylated in the event of DNA damage, and causes transcription for the translation of p21 which inhibits G1/S and S-Cdks preventing DNA synthesis. Mutated in half of cancers |
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Blebs |
Irregular cell buds on a cell undergoing apoptosis |
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Phosphatidylserine |
Signal that promotes phagocytosis |
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Procaspases |
Cleave themselves to form capsases by induced proximity or are cleaved by capsases. Induced proximity is signaled for externally or caused by cytochrome C assembling the apoptosome wheel internally. |
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Cytochrome C |
Released from a mitochondria that received an internal apoptosis signal (Bcl-2) and causes the apoptosome to form inducing the caspase cascade. |
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CAD |
Caspase Activated DNAse Released from its inhibitor iCAD by an executioner caspase and cuts DNA |
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Bcl-2 family |
Effector: Will aggregate on the mitochondrial membrane which causes cytochrome C release resulting in apoptosis Anti-apoptopic: inhibit aggregation of the effector Bcl-2 proteins so apoptosis does not occur |
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IAP |
Inhibitor of Apoptosis An external survival factor inhibits anti-IAPs so IAPs are free to inhibit apoptosis |
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Cadherins (4 types) |
Link cells together through their extracellular domains in the presence of Ca2+ which makes them rigid (Ca-adherents). Differences are responsible for tissue segregation by type. Classical: N- (nerve), P- (placenta, epidermis), E- (epithelial) Non-classical: desmosomes and involved in neurons |
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Integrins |
Link cells to the ECM. On the ECM side the link is mostly to laminin, fibronectin, and collagen. Allows for signaling both ways. Can also bind to other cells through Ig-like CAMs. Ca2+ or Mg2+ dependent. Active when the alpha-beta-glycoprotein heterodimer is straight |
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Adherins junctions |
A type of cadherin. Link actin from one cell to another |
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Desmosome junctions |
A type of cadherin. Link intermediate filaments from one cell to another |
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Focal adhesions |
Link actin filaments to the ECM |
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Hemidesmosomes |
Link intermediate filaments to the ECM |
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Malignancy |
The spreading of cancer. 90% of cancer is epithelial. If malignant it stops expression of E-cadherin, detaches from the epithelia, and migrates elsewhere. |
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Beta-catenin |
When Wnt is present it is stable and helps to link classical cadherins to actin |
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Alpha-catenin |
Helps to link classical cadherins to actin. When stretched it had more room to bind vinculin which binds more actin. |
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Transcellular network |
Actin/myosin bundles around cells (belts) that are connected and can contract to form invaginations |
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Tight (occluding) junctions |
Selectively permeable barrier between cells that pinches together at the apical surface and keeps apical (active) and basal membrane (passive) pumps separate |
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Paracellular vs Transcellular transport |
Paracellular: passive, small molecules go through tight junctions between cells Transcellular: active/passive, molecules go through the cells |
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Claudins and occludins |
Form tight junctions by homophilic interactions. Claudins can form paracellular pores |
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ZO |
Zonula Occludins Serve as a scaffold for tight junctions |
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Gap junctions |
Channels between cells that allow through molecules <1000 Da (1 Da = 1g/mol). Gap junction signalling is faster than through synapses but less regulated. Allows for synchronous contractions of heart/smooth muscle |
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Connexins/Connexons |
Connexins are monomers that make up connexons (6 connexins). Connexons from opposite cells link to form a continuous channel. There are several thousand channels per gap junction |
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Selectins (3 types) |
A type of CAM (Cell adhesion molecule) that weakly binds to oligosaccharides. Responsible for immune responses. Ca2+ dependent Types: L- (leukocytes), P- (platelets), E- (endothelial (blood vessels)) |
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Immunoglobulin superfamily |
A type of CAM (Cell adhesion molecule) that have Ig-like domains that are not Ca2+ dependent and can bind to themselves or to integrins |
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Fibroblasts |
Cells that secrete extracellular matrix |
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Connective tissue ECM |
Consists of fibrous polymers, ex: collagen, fibronectin, etc. |
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Extracellular matrix components |
Proteoglycans, fibrous proteins, and glycoproteins |
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Proteoglycans |
Consist of GAGs attached to proteins linked through a serine amino acid (99% saccharides) |
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GAGs |
Repeated unbranched disaccharides that are negatively charged |
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Hyaluronan |
A GAG that along with proteoglycans forms hydrating gels. It is negatively charged so attracts Na+ which attracts water because of osmotic pressure
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Aggrecan aggregate |
A core protein attaches a lot of hyaluronan which attaches a lot of proteoglycans which have a bunch of GAGs. The major proteoglycan in articular cartilage |
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Collagen |
The major protein of connective extracellular matrix. Three intertwined L-alpha-helixes that make a right-handed spiral. Every third residue is glycine. Assemble into stiff fibrils |
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Fibronectin |
A glycoprotein. Glycoproteins are about half protein and half polysaccharide and help with extracellular matrix orgaization by binding to components of the matrix and to integrins |
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Basal lamina |
A type of ECM made of glycoproteins and proteoglycans in a thin mat that underlies epithelial cell sheets and tubes, surrounds individual muscle cells, and is a selective filter in kidneys |
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Basal lamina synthesis |
Made by cells on both sides, i.e. epithelial and stroma (cells in the connective tissue (connective ECM)) |
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Basal lamina connections |
Epithelial side: through integrins Connective tissue side: through fibronectin |
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Laminin |
A heterotrimer glycoprotein responsible for basal lamina organization (sheet structure) |
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Talin |
Recruited by thrombin in blood clotting. Is an adapter between active integrin and actin on the intracellular side. This makes extracelluar side sticky (blood vessel walls). When talin is pulled it has room to bind vinculin which recruits extra actin |