main properties of?

MTs

Actin

IFs

organelle location and division

locomotion, cytokinesis, exo/endocytosis

strength

actin fibers

thymosin sequesters free monomers therefore stabilizing the growth of actin.  

profilin has the opposite effect bc it aids in the addition of free ATP bound monomers

on the interior side of the PM, there are adherent junctions and focal adhesions which serve as connection sites for actin internally, but are adhesion site for cell to cell contact on the exterior

cadherins will be connected to these proteins extracellularly and span a protential space until they connect with a neighboring cells.  The intracellular tail of the proteins is connected to actin, and is therefore, significanly anchored

at desmosomes (cell to cell) and hemidesmosomes (cell to matrix).  the filaments at alpha helical.  they arrange in tetrametic subunits where two alphahelical stands are lined up, but they are anti parallel to two other monomeric stands with their amino groups facing the other's COOH groups

therefore, lack polarity, can have no motor proteins 

in epithelial cells, they are usually connected to desmosomes through desmolein and desmocollin via kertin fibers

the fibers connected at basil lamina are connected through integrin AB and plectin at hemidesmosomes

present in all cells, has single head and tail.

the tail may bind a vesicle, the PM, or an organelle

conventional myosin, found in muscle cells, is a dimer with two heads

each head will attach to different F-actin molecules (at amino head) and the two tails will attache to the two tails of another myosin 2 dimer (at COOH head)

makes contractile activity possible and cytokinesis

unconventional

double heads bind to actin while the globular tails can bind to a Rab protein on a vesicle.  works in vesicle transport and can move in both directions

moves melanosomes

what is the malfxn in osteogensis imperfecta?

ehlers-danlos syndrome?

weak bones due to a collagen type one mutations

collagen type two mutations causing chondrodyplasias (abnormal cartilege)

by cells with regulate their deposition over the plasma membrane sometimes done so by secretions that mediate their interactions with each other.

skin fibrils are women into a wickwork patter, tendon are organized in parallel bundles, bone and cornea are arranged in an orderly ply-wood style configuration

it is a very hydrophobic and is rich in proline and glycine, however, unlike collagen, cannot be glycosylated or hydroxylate lysines.

comes in alternating segments of (1) lysine and alanine a helicial segments and (2) hydrophobic segments

tropoelastin, the elastin precursor, is soluble

the lysines get widely crosslinked once the elastin precursor has been transported outside the PM.  the elastin network then gets covered by MAGPs (microfibril-associated glyxoproteins; such as fibrillin-1 and -2)

deficiencies in formation of fibrillin-1 can lead to marfan's syndrom (lanky with spidery fingers and narrow aorta)

polysaccharide chains called glycosaminoglycans (GAGs).  this produces very hydrated "ground substances" which embed in collagen and elastin (space is created this way and prevents too tight of packing; also, molecules are able to pass through the ECM with this space created)

these proteins are sythne. by RER and GAGs are assembled on them inside the golgi

very hydrophilic, negatively charged by carbonyl and sulfate, therefore will attract Na+ which will draw water out extracellularly and take on a very extended conformation

types include:

hyaluronan

chondroitin/dermatan sulfate

heparin

keratan

a transmembrane protein which has extracellular GAGs connected to chondroitin sulfate and haparin sulfate, while its intracellular doman is attached to the actin cytoskeleton.

this positioning allows it to act as a receptor for matrix proteins

they modulate integrin fxn at focal adhesions in fibroblasts and can bind fibroblast growth factors and present them to FGF receptor proteins on the PM of the same cell

simplest and largest of GAGs with 25,000 repeating dissharide units.  it is abundant in early embryos as it plays the role of a space filler during development (almost the size space of an organelle)

also big enough to create a cell free space which allows for the important migration of cells forming the heart and cornea during development

can allow passage of Wharton Jelly

has two subunits bound by sulfide bonds.  the two subunits have sollagen bind, cell bind, heparin binding domains.  each domain has "modules" too.  The main ones in fibronectin binds to integrin.  basically it can just glue everything together

these are found on the interior of the cell and are attached to actin.  actin helps influence fibronectin orientation and can pull on the fibronectin until they begin to display a cryptic domain allowing them to bind to each other (sometimes disabled in cancer cells allowing them to break apart from each other and metastasis).

this fibronectin/fibril relationship can be inhibited by uteroglobulin in the kidney

a large protein that can self-assemble in vast 2D networks.  very important component of basal lamina.  the laminin can bind to perlecan type IV collagen, and nidogen and holds all the components of the basal lamina together making a nice sheet.

it is also capable of signaling down an integrin to stimulate things such as cell proliferation.

the ECM has to be able to turnover and deconstruct in response to events such as the need for cell migration, infection, injury, tissue remodeling.

this is done by extracellular proteases.  in normal tissues, this happens slow and naturally, and continuously

there are two classes of these protease, metalloproteases (MMPs) and serine proteases (some members are chymotrypsin, tyrpsi, elastase).

most components mentioned are degraded extracellularly, but proteoglycans and hyalauronans under endocytosed and brought to lysosomes for degradation

The action of proteases is restricted by protease inhibitors:

integrin can stimulate the ECM of other cells it comes in contact with and can propogate orginization with any cells in the vacinity if its environment demands it to do so.

this is also beneficial to the cells that were floating around because many need to be attached to survive (known as anchorage dependence).  binding causes vital signal transduction

fibronectin as well as integrin are very important in this process

cells may need to perform locomotion in order to find other cells in which to associate their ECM with.  Actin will play the major role in this, as per usual, but proteins like fibronectin can also help.

they help by forming adhesions as it moves to find a cell to associate with

Basal lamina is synthesized by :

help it to determine:

the cells that rest on it

cell polarity,

influence cell metabolism,

organize the proteins in adjacent plasma membrane,

promote cell survival,

proliferation,

differentiation,

serve as specific highways for cell migration. 

mature basil lamina contain type IV collagen

what does ___  do?

MYC

HER2/neu

BCL2

it is a transcription regulator

activates EGFR

anti-apototic gene