endocytosis

Which are the two kind of endocytosis

1. Phagocytosis ( ingestion of large partciles) to take up nutrients es. Macrophage, neutrophils…

2. Pinocytocis ( uptake of fluid)

Steps from pseudopia extension to digestion of the pathogen

1. There is the pssueudopodia extension from the specialized cell

2. Engulfment and formation of a phagosome

3. Fusion with lysosome

4. Pagolysosome

5. Digestion

Is phagocytosis triggered or continous

Its CARGO TRIGGERED

It requires the activation of cell surface recpetors

If the pathogen are covered by antibodies how doesthe phagocytosis happen

1. Patogen are covered with AB

2. This antibody that cover the patogen BIND with the FC receptor on the macrophage ( or other)

3. Fc of the ab and fc of the macrophage makes engulfment passible

What drives pseudopod extension and the phagsome formation

Its ACTIN DRIVEN it depends on the polymerzation or depolym. Of actin!!!!!

The polym and depo. Depend on phophoinosited in the membrane of the forming phagosome

To shape pseudopods what is the role of RHO gtpase

Where are the phophoionistied located

Rho gtpase activate PIKinase to produce PI(4,5)p2 in the membrane this stimulates actin polynmerization that allows the psuedopod extension and phagosome formation

The phophiosinoties are present in the membrane of the forming phagsome

How is the phagosomw sealed ( è concluso e ha completeato l engulfment)

Through ACTIN DEPOLYMERIZATION that allows it to seal off the phagosome and complete the engulfment

Actin is depolimerized beacuse PI3 makes pi45 become PI 3, 4,5, P3

PI 4, 5 P2 triggers actin polym or depolum

Polymerization

PI 3, 4,5, DEPOLYMERIZATION

What very famous bacterium makes phagosome acidification ihibited??

Tuberculosis

Pinocytosis

Is it actin dependent as phagocytosis?

Is it cargo triggered?

Pinocytosis is not stimulatd is not cargo triggered it is CONTINOUS

It is not actin dependnent or with pseudopodia it is with VESCICLES

In the case of MACROpinocytosis which projecion allow to internalize extracellular fluid

LAMELLIPODIA

In normal pinocitosis this does not happen

Because it is vescicle mediated

How is esocytosisi and endocytosis in equilibrium ( la quantita di membrana

The same amount of membrane Removed by eso = afded by endo)

50% of cell membrane is replaced every hour!!!! Only 5% is new

Usually which is a signal for endocytosis

It is a 6 AA long WITH TYROSINE that it us taken up via clatherin coated pit ( clatherin va in entrambe le direzione TGN/PM

Clatherin allow endocytosis ( pm to cell inside) descirbe the structure of the basket

What allows to pinch off the budding formed?

Its a TRSIKELION formed by 3 heavy chains and 3 light chains

To allow the budding to then be pinched off ( hai il berncoloino e lo devi togliere) there are DYRNMINS

What do dynamins do

Cut off the budding formed by claterhin

Gtp ase

Claterin was important to study which disease

FH family hypercolesterolemia As colesterole is not soluble and it is transported in the bloodstream in form of LDL low density lipoprotein

What makes ldl to be accumulated in F hypercolesterolemia

What are biding defects?

BINDING DEFECT There is a mutation in the receptor so o no ldl binds to ldl recpetos

INTERNALIZATION DEFECT: ldl receptor is bidned but do not do the coated pits

PCSK9 function

PCSK9 binds the LDL receptor and redirects it to LYSOSOME

So the ldl recpetor are not recycled but degradated less ldl can be bond so you have much more ldl in the blood

Why are ANTI pcsk9 a possible treatment

Anti pcsk 9 inhibit pcsk9 so hat ldl recpetors are not degardated in the lysosome

What is ldlr

LDLR iis the onne that allow ldl to go to recyling

Endocyting pathway of iron

What blood glycoprotein control the fe levels?

What happens when iron is released

TransFERRIN

Taking up if the receptor of fe makes it go inthe cell with endocytosis

THE RECEPTOR for transferin and FERROTRANSFERIN enter the cell

Low ph makes fe to be released but ferro tranferin stay bind to the receptor

Apotrasnferin is recycled back into a membrnane and then dissociates

FERROTRANSFERIN: fe+transferin

APOTRANSFERIN: tranferin che ha gia lasciato il ferro nella cellulla

How maternal antibodies are passed to baby is a process of

RECEPTOR-mediated endocytosis and ESOCYTOSIS = TRANCSYOSIS