Phospholipid structure

1
Phospholipid structure
Amphipathic molecule (phosphatidyl
choline) hydrophobic part fatty
acids hydrophilic part phosphate choline
2
Membrane structure
3
Membrane components
4
Transmembrane proteins
5
Intercellular structures
Desmosomes spot welds, dense proteins
(cytoplasm intercellular) fibers
(intermediate filaments) extend across
cells epithelial cells (especially skin),
cardiac intercalated disks Tight junctions cell
collar, block large molecules, no lateral
protein movement epithelial cells Gap
junctions cell-cell communication, small
molecules (lt1000 MWt) cardiac intercalated
disks, smooth muscle
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Desmosomes
spot welds, dense proteins (cytoplasm
intercellular) fibers (intermediate filaments)
extend across cells epithelial cells (especially
skin), cardiac intercalated disks
fig 3-10a
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Tight junctions
cell collar, block large molecules, no lateral
protein movement epithelial tissue (esp. kidney,
gut)
paracellular pathway between cells
fig 3-10b
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Gap junctions
cell-cell communication, small molecules (lt1000
MWt) cardiac intercalated disks, smooth muscle
fig 3-10d
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Epithelial cell
fig 3-10c
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Protein ligand interaction
Proteins could be Ligands would be enzymes
substrates, allosteric regulators receptors ch
emical messengers transporters transported
substances transcription factors transcription
regulators any of above drugs
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Protein-ligand binding properties
Specificity binding depends on ligand size,
shape, charge Affinity strength of binding
i.e. ligand at 50 binding Saturation there
is a finite number of binding sites Competition
structurally similar molecules can compete for
binding
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Specificity
binding depends on ligand size, shape, charge
fig 3-27
fig 3-26
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Specificity
protein Y specificity greater than protein X
specificity
fig 3-28
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Affinity
strength of binding i.e. ligand at 50 binding
fig 3-29
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Affinity saturation
strength of binding i.e. ligand at 50 binding
fig 3-30
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Affinity (different proteins)
strength of binding i.e. ligand at 50 binding
fig 3-31
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Affinity (different ligands)
strength of binding i.e. ligand at 50 binding
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Protein-ligand binding properties
Specificity binding depends on ligand size,
shape, charge Affinity strength of binding
i.e. ligand at 50 binding Saturation there
is a finite number of binding sites Competition
structurally similar molecules can compete for
binding and remember the protein can be an
enzyme, receptor, transporter, etc.
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Regulating binding site properties
a. Allosteric modulation reversible binding at
another (allo-) site can be activation or
inhibition
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Regulating binding site properties
a. Covalent modulation chemical alteration of
the protein can be activation or inhibition
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Metabolism (pathways)
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Metabolism (key)
Key A glycogenesis, B glycogenolysis, C
glycolysis, CD anaerobic glycolysis (lactic
acid fermentation), E gluconeogenesis, F
irreversible step (pyruvate dehydrogenase), G
protein synthesis, H proteolysis, I
lipogenesis, J lipolysis, K Krebs cycle,
L urea synthesis, M ketogenesis Anabolic
pathways A, G, I Catabolic pathways B, C, E, F,
H, J, K Liver only E, L, M Mitochondrial
K Ribosomal G Smooth endoplasmic reticulum I
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Energy content