cytoskeleton

Question 1

AF functions

Answer 1

1) cortical web supports cell membrane+maintain shape. web attached to proteins SPECTRIN+DYSTROPHIN
2) anchored in zonula adherens+focal adhesions= supports microvilli+stereocilia forming stress fibres +contractile ring for cytokinesis
3) works w myosin motor protein for transportation+ extend cellular process creates small protrusion = FILOPODIA on the surface
myosin motor proteins (12 classes, head has no actin binding site,instead has ATPase. has tail+neck. only myosin 6 associated retrograde mov rest is anterograde (+)

Question 2

all actin binding proteins ?

Answer 2

actin bundling proteins, actin linking proteins, actin fil severing, actin capping, actin branching and anchor proteins

Question 3

actin bundling proteins

Answer 3

create actin fil bundles. thicker structure helps support +providing rigidity. uses VILLIN+FIMBRIN+ALPHA ACTININ

Question 4

cross-linking proteins

Answer 4

creates interconnected fibres using FILAMIN

Question 5

actin capping

Answer 5

blocks sites (at ends) that help regulate the shape+size

Question 6

AF

Answer 6

thin fil, 6-8nm, G actin monomers organized in double helix=F actin fil
- G actin concentrated along cell cortex
- grow by G actin monomers adding to preexisting fil,by pool of G actin monomers using nucleation factor FORMIN or by branching points

Question 7

actin assoc w cytokinesis

Answer 7

process where cell divides into two daughter cell after mitosis. uses contractile ring (bc anchored to zonula adherens+focal adhesions
associated w myosin II, constriction-> cleavage of cells

Question 8

actin assoc w myosin I

Answer 8

changing shape of cell during endocytosis, exocytosis, and locomotion

Question 9

actin assoc w cytoplasmic vesicles

Answer 9

granules+melanocytes play role in mov

Question 10

actin fil severing

Answer 10

use GELSOLIN to cut to shorter seg

Question 11

actin branching

Answer 11

filament can grow by producing branching points

Question 12

why actin fil highly dynamic

Answer 12

increase size of monomers, added to barbed end (+) by hydrolyzing ATP. remove on (-). this process cause migration of subunits through treadmiling. uses PROFILIN+COFILIN

Question 13

Actin assoc w sk

Answer 13

actin integrated w thick myosin fil
contraction- shorten cells or retract cellular processes causes by stretching antiparallel stress fibres (has actin)