Phosphatidylserine Flashcards
phosphotidylserine
important for memory/cognition
phosphotidylcholine
major constituent of cell membrane, and pulmonary surfacant
phosphotidyethanolamine
composing 25% of all phospholipids, found in nervous tissue such as white matter
diphosphatidylglycerol
cardiolipin, found in inner mitochondrial membrane
distinguish sphingomyelins from glycolipids and phosophoglycerides
phosoglycerides are connected to a glycerol via an ether bond: simplest form is phosphotidate
-two fatty acids using ether bonds to glycerol, which has a phosphate group attach to it’s end alcohol
sphingoymyelin uses a sphingosine instead of a glycerol and an amide bond to its fatty acid tails; it’s phosphate attached group is a phosphorylcholine.
glycolipids use the amide bond to the fatty acids, and have a sugar connected to its alcohol instead of a phosphate group
Cerebroside
a glycolipid
archea
resistant to pH and temp changes because of ester bonds to fatty acid chains
micelles versus bilayer formation
membranes have to be treated with detergents or salts to disrupt their associations; single lipids can then form micelles, without the detergent to they prefer the bilayer
F.R.A.P
fluorescence recovery after photo bleach technique
lateral movement versus flip flops
proteins move laterally, no flip flops except once in several hours
membrane asymmetry
interior and exterior are different in appearance
Site of glycosylation of membrane
ECM side; no glycosylation occurs on the inside membrane of the cell
glycocalyx
important feature in cells, especially epithelia with microvilli
- cell signaling
- act as antibodies that target foreign carbohydrate molecules
Where is cholesterol found in cell membranes?
large amounts are found in both leaflets
RME
utilizes fusion of a vesicle to a membrane, protein and snap involved
mitochondrial fission
postulated mechanism for mito division, not simple pinching but more along side bacterial fission
mitochondrial fusion, definition and requirements
“salvage” process involving organelle collision
one will fuse with another to save it; if it’s beyond repair it will be destroyed
requirements: sufficiently large electrochemical gradient must be present across the inner membrane
elevated GTP levels must be available for hydrolysis
Protein imports into mitochondria
Protein import: protein has to be unfolded, thread through, and then reassembled in the interior, inner and outer membranes form transient channels between themselves
ATP dependent
Membrane proteins
Monotopic, bitopic, polytopic = integral
protein associated, acyl anchored, phospholipid associated = associated polypeptides
transporters are mostly
polytopic, transmembrane, integral membrane proteins
List of integral proteins
monotopic: cytochrome b5
bitopic: receptor tyrosine kinase
polytopic: plasma membrane calcium ATPase (PMCA), sodium channel, calcium channel
List of membrane associated proteins
protein to protein: calmodulin
protein attached to phospholipid: annexin, spectrin
protein attached to acylation: nitric oxide synthase
protein attach by carbohydrate GPI anchor: Thy 1
Plasma membrane facts
asymmetric
semi permeable
lipophilic molecules cross via diffusion
impermeable to hydrophilic/polar molecules- need transport mechanism
membrane proteins facilitate the transport of specific molecules across the membrane
What governs the biochemical/metabolic characteristics of a cell?
expression of specific transporters: can execute only those reaction whose substrates can be take up
a means of regulating metabolism might involve
altering expression of transporter levels
free energy is associated with what kind of arrangement of molecules?
unequal distribution
establishing a gradient implies that
ATP was used in setting up the gradient
free energy is stored
by a previous expenditure of ATP
Uncharged Molecule Formula
alpha G = 2.303 RT log 10 (C2/C1)
R is the gas constant
T temperature
C1 is the concentration on side 1
C2 is the concentration on side 2
Charged molecule Formula
2.303 RT logs subscript 10, (c2/c1) + ZFV
Z= electrical charge of the transported species
F= Faraday’s constant
alpha V = membrane potential
Equilibrium constants
C1 = C2
G = 0
+ values for G mean active transport
P type ATPases
- 70 proteins in human genome
- integral membrane proteins
- utilize ATP hydrolysis to transport against gradients
- Transporter forms a covalent bond with the phosphate to form an enzyme phosphate intermediate
- Phosphorylation on a conserved aspartate residue
P type ATPase details
- establish a gradient using ATP (transforming it into ADP)
- forms covalent bond with phosphate to form “enzyme-phosphate” intermediate
- phosphorylation occurs on an aspartate residue
Sodium Potassium Pump, stoichiometry ratio and percentages
3 Na; 2 K/ mol ATP
24-40% of brain ATP used by the Na pump
Ouabain/digitoxigenin
cardiac glycosides that inhibit Na/K ATPase activity
lowers Na and inhibits Na-Ca pump activity, but increases overall Ca concentration, so increases contractile force of cardiac muscle
used in treatment of congestive heart failure and dysrythmias
Calcium as a Signaling Molecule
10,000-fold ECM concentration of Ca across plasma membrane
asymmetry of membrane critical for signaling in
neurotransmission
learning and memory formation
muscle contraction
gene expression
Types of Calcium
j
P Type ATPases (kinds)
PMCA
SERCA
Na-K-ATPase
H-K-ATPase
Apart from the P type ATPases, name another kind of ATP utilizing proteins
ATP cassette transporters
multi drug resistance protein
Calcium Regulatory Systems
Calmodulin (Ca binding protein) SERCA: calcium uptake proteins in the SR PMCA: main cell membrane calcium regulator Na-Ca exchanger (anti-porter) (secondary active transport) calcium channels (voltage/ligand gated) Ryanodine receptors TRP channel IRP receptor
PMCA: how it works
pumps calcium to extracellular side
transports 1 Ca/1 ATP
stimulated by calmodulin
plays important cole in calcium homeostasis an in neuronal signaling
