intermediate filaments and septins

do intermediate filaments have polarity like actin and tubulin

no

what are the two ends of the intermediate filament called

• N terminal

• C terminal

what is the basic unit of an intermediate filament

A tetramer

what are cytoplasmic versions of intermediate filaments

• keratins

• neurofilaments

• vimentin

what are keratins

they keep cells intact and together against mechanical stress

are septin polymers polarized like actin

No

what is specific to septin polymer makeup

they are two fold rotation symmetry axis

Do polymerized septins form higher structures

They form paired filaments, rings and sheets

what does septin organization depend on in mammalian cells

It depends on actin

what is the functions of septin

• promote cell asymmetry as diffusion barriers

• provide rigidity to the cell and restrains membrane bound proteins

what is cell polarity necessary for

it is crucial for development and specialized cell function as well as normal development

what is RAS

It was the first oncogene found in human tumors and important in cell regulation

How do Rho and Ras Gtpasases influence the function of the cell.

When bound with GTP the molecules promote actin polymerization

does septin bind any nucleotides

They bind GTP

What do Rho and Ras do to the cell when activated

When activated they regulate the polarity of the cell by promoting the growth of actin

what two enzymes regulate activation of Rho

• GEF(GTP exchange factor)

• GAP(GTPase Activating Protein)

How can we determine where/when RHo is activated in vivo

GTPase biosensors are designed based on the GTPase binding motif of the effectors

what activates formins

Rho GTPase directly

what activates Arp complexs

Rho GTPase → Nucleation promoting factors

Rho gtpases effect cell migration by manipulating the actin arrays within the cell. What names are given to 3 most commonly manipulated actin arrays.

• Filopodium

• lamellipodium

• stress fibers

what two forms of GTpases causes formation of the leading edge ( filopodia, lamellipodia)

• Cdc42

• Rac

what from of GTpases causes formation of stress fibers

• Rho

alongside FH1 domains and FH2 domains what nuclear domains do formins have that indicate that they require the activation of Rho to funciton

formins have a GTPAse binding domain