-
charge of the mitochondria matrix
negative charge
-
general characteristics of mitochondria presequence
- usually n-terminus
- hydrophobicÂ
- positive
-
steps to transport peptide to mitochondrial outer membrane
- hsp70 binds hydrophobic presequence and goes to mitochondria
- TOM-translocase of outer motichondrial membrane
- SAM- refolds protein into outer membrane
-
TOM
translocase of outermitochondrial membrane
-
SAM
sorting assembly mechinery
-
TIM
translocon across inner mitochondrial membrane
-
transport of peptide to mitochondria matrix
- TOM to TIM23/17
- MPP cleaves targeting sequence
-
trasport peptide to innermitochondrial membrane
- TOM to TIM 22 which export peptide into the membrane
- signal not cleavable
-
tiny TIMS
- low molecular weight proteins that live in the intermembrane space
- mostly chaperones and folding proteins
-
transport peptide to intermembrane space
- TOM to TIM 23/17
- TIM to MPP cleave targeting sequence
- TIM 44 transports sequence to intermembrane space
-
Proteins and process involved in peptide transport into chloroplasts
- TIC TOC proteinsÂ
- similar mechanism as mitochondria
-
Endoplasmic reticulum
- site of production and the beginning of processing of proteins that are not cytoplasmic
- lipid production
- small molecule production
-
examples of ER processed proteins
membrane and secreted proteins
-
remember structure of ER
paltes, rough ER, smooth tubular structures
-
do all cell types have the same amount of smooth and rough ER
naw son
-
what does the smooth ER produce
cholesterol, hormones, membrane phospholipids, drug detoxification
-
structure of export domains in the ER
regions in the ER that are branched so vesicle can bud and transport
-
where is calcium stored
ER
-
proteins involved with manipulation and maintaining smooth ER structure
- reticulons: alpha helical proteins assist in bending of plasma membrane and cause it to form tubular structure
- atlastins: GTPases exist at the branch point, GTPase activity causes the fusion of 2 tubule membranes
-
relationship between cytoskeleton and ER
ER binds side of microtubules and can be moved as microtubules move
-
how to get proteins into the ER
cotranslational insertion governed by n-terminus signal sequence
-
cotranslational insertion into the ER steps
- free ribosome in cytoplasm starts translation
- translated signal sequence binds SRP
- SRP binds and inactivates a couple of elongation factors and pauses the ribosome
- SRP diffuses to the ER and binds to SRP receptor and translocon
- SRP and SRPR when in contacts hydrolyze their GTPs
- SRP and SRPR dissociates from translocon Sec61
-
proteins involved in transport of protein into ER lumen
- powered by ribosome w/ chaperone help BiP
- binds specific hydrophib portions and ratchet the polypeptide into the ER
- other chaperones help with folding
-
chemical characteristics of the ER
really crowded, oxidizing environemnt, favorable for disulfide bonds
-
transmembrane proteins in the ER
- Type I: n-terminal in the ER, contains stop transfer sequence at the beginning
- Type II: N-terminal in the cytoplasm, contains an internal start transfer sequence
-
features of post-translational insertion
- common in yeast, and bacteria
- rare in vertebrates
- usually small proteins
- includes some tail-anchored
-
where does disulfide bond formation takes place
in the ER
-
what enzyme catalyzes disulfide formation
protein disulfide isomerases
-
difference between lipids in the ER and golgi/plasma membrane
- contains more unsaturated lipids (kinks)
- more flexible
- more dynamic, favors folding
-
protein modifications that occur in the ER
Glycosylation, disulfide bond formation, folding
-
where do preassembled sugars attach in the ER
attach to asparagine residues
-
Relationship between protein degradation and sugars
ER degrades sugars over time and eventually signals ERAD
-
what events can signal ERAD
- protein misfolding which leads to aggregations
- overexpression, stress overload the ER
-
ERAD
- ER -associated degredation
- mutants are translocated back through sec61 into the cytoplasm and proteolysis
-
CTFR
- cystic fibrosis (recessive gene)
- chloride channel in the ER
- mutation make protein stay in the ER
-
HMG-CoA-reductase
on of the last enzymes in biosynthesis of cholesterol
-
hypercholersterolmia
- result of over activity of HMG-CoA reductase
- males too much cholesterol
-
drug used for hypercholesterolmia
statins- they inhibit HMG-CoA-reductase
-
where does lipid production take place
- on cytoplasmic leaflet of the ER bilayer
- flippases flip the lipid enzyme
|
|
