BIO 464 - Cell Adhesions

Plants came about when what single celled organism evolved multicellularity?

Algae

Fungi came about when what single celled organism evolved multicellularity?

Yeast

Animals came about when what single celled organism developed multicellularity?

Choanoflagellates

In animals, cells must associate with each other and what structure?

Extracellular matrix

How many types of cell adhesion molecules are there?

Four

What are the types of cell adhesion molecules?

Cadherins, IgCAMs, Selectins, Integrins

What feature of cadherins allows them to bind calcium molecules?

Cadherin repeats

IgCAMs use what feature in order to bind substrates?

Immunoglobulin repeats

What domain allows selectins to bind carbohydrates?

Lectin

Integrins bind to what?

The extracellular matrix or other cells

Epithelial cells form _____ that line _____.

Sheets, organs.

What is the largest example of epithelial tissue? (AKA: your largest organ)

The skin

Which surface of an epithelial cell faces the lumen?

Apical surface

Which surface of an epithelial cell faces the ECM?

Basal surface

Which surfaces of epithelial cells face adjoining epithelial cells?

Lateral surfaces

The basal face and lateral faces of epithelial cells are collectively known as what?

Basolateral faces

Epithelial cells form what junctions?

Anchoring junctions

Anchoring junctions between epithelial cells include:

Adherens junctions, desmosomes, tight junctions, gap junctions.

What anchoring junction is found between epithelial cells and the ECM?

Hemidesmosomes

Where on epithelial cells are adherens junctions found?

Near the apical surface

E-cadherins are the CAMs used in adherens junctions in what type of cells?

Epithelial

N-cadherins are the CAMs used in adherens junctions in what type of cells?

Neurons

How do cadherens link neighboring cells?

They have short transmembrane domains

The portion of the cadherin transmembrane domain in the cytosol links to what protein?

β-catenin

Aside from cadherins, β-catenin links to what protein?

α-catenin

Aside from β-catenin, α-catenin links to what protein?

Actin cytoskeleton

How does β-catenin act as a signaling molecule?

When free floating, it travels to the nucleus and prevents apoptosis

What happens if free floating β-catenin is destroyed in the cytosol?

Apoptosis occurs

How does β-catenin become free floating?

Cells pull apart, unbinds cadherins and α-catenin

How can β-catenin induced apoptosis be prevented?

Hormones

What are the CAMs in desmosomes?

Desmosomal cadherins

The transmembrane portion of desmosomal cadherins binds what protein in the cytosol?

Plakoglobin

Plakoglobin binds what protein in the cytosol?

Intermediate filaments/keratin

What type of cell junction prevents cells from being ripped apart by force?

Desmosomes

Hemidesmosomes perform what function?

Anchor cells to the basal lamina

What protein do hemidesmosomes use to bind?

Integrins

Integrins are what kind of protein?

Transmembrane

Integrins bind to what in the cytosol?

Keratin

Adherens junctions perform what adhesion type?

Cell-cell

Desmosomes perform what adhesion type?

Cell-cell

Hemidesmosomes perform what adhesion type?

Cell-matrix

Tight junctions perform what adhesion type?

Cell-cell

Gap junctions perform what adhesion type?

Cell-cell

What two subunits make up an integrin?

α&β

When integrin subunits are pushed together, they ______ bind their substrate.

Cannot

When integrin subunits are pulled apart, they _____ bind their substrate.

Can

Binding of integrins to their ligands causes them to what? What type of cell signaling is this?

Straighten out, outside-in.

Cytosolic proteins can force integrin subunits together, or pull them apart. This is what type of cell signaling?

Inside-out