Cells to Tissues Flashcards
adhesive structures
tight junction, adherens junction, spot desmosome, hemidesmosome, gap junction
tight junction (adhesive proteins, substrate, & function)
adhesive proteins: occludin, claudin, JAMs
bind to: actin filaments
function: prevents materials from moving in between cells (can also serve as receptor and entryway for viruses - especially in the intestine)
adherens junction (adhesive proteins, substrate, & function)
adhesive proteins: cadherens
bind to: actin filament
function: form part of the circumferential belt to give structure/stability to the cell
spot desmosome (adhesive proteins, substrate, & function)
adhesive proteins: desmosomal cadherens
bind to: intermediate filaments
function: attach to intermediate filaments
* made of cytoplasmic plaque associated with desmoglein and desmocollin
hemidesmosome (adhesive proteins, substrate, & function)
adhesive proteins: integrin α6ß4
bind to: intermediate filaments
function: attaches cell to basal lamina (keeps cells in position & associated with ECM in order to survive)
gap junction (adhesive proteins, substrate, & function)
adhesive proteins: connexins, innexins, & pannexins
bind to: indirect connection to cytoskeleton
function: communication - allows diffusion of small molecules between cells
two types of cadherens
E-Cadherins & desmosomal cadherin
E-Cadherins
found in adherens junctions
homophillic interaction: associate with another cadherin on extracellular side / interact with catenins that attach to circumferential belt
desmosomal cadherin
made up of desmoglein and desmocollin;
different regions of a polarized cell in a tissue
apical
lateral
basal
apical domain
interacts with surface
lateral domain
nteracts with/ is connected to adjacent cells
basal domain
interacts with the basal lamina
integrin
multi adhesive protein; transmembrane heterodimers (α & ß chains) that interact with ECM; can have outside-in & inside-out signaling
outside-in signaling
integrin responds to outer ligand binding, conformation change passes through the molecule, across the plasma membrane, and induces change on the cytoplasmic side
inside-out signaling
growth factor receptors (GFRs) can activate the integrin tail and induce conformation change on the outside of cell that alters ligand affinity
basal lamina
region directly under the cell (generally in polarized epithelial cells); specialized form of ECM
components common to all basal lamina
Type IV Collagens
Perlecan
Entactin
Laminin
How is basal lamina formed?
Generated / secreted by the cells
What are collagens?
Trimeric helix structures that form a network in the basal lamina & can interact with other proteins. Have unique synthesis process that begins in the rough ER and is completed outside the cell.
How do the collagen isoforms differ?
size & structure, associations, function, & tissue
notable collagen isoforms
Types IV, I, & II
Type IV collagen
found in the basal lamina - makes up the framework
Type I collagen
found in tendons - gives strength
Type II collagen
found in cartilage - absorbs shock and gives strength
general structure of collagen
C-terminal globular head
Trimeric helix
Small N-terminal globular domain
What makes collagen unique?
it’s synthesis
How is collagen synthesized and secreted?
Formation begins in the Rough ER; Propeptide (has additional peptides to prevent premature folding); Procollagen forms triple helices; Moves through the Golgi Apparatus; Lateral association begins; Excreted out of the cell by golgi dependent vesicles; Propeptides are cleaved; Assembly & crosslinking of fibrils
proteoglycans
Molecule with a protein backbone and very large sugar dimers
GAGs
glycosaminoglycans - large sugar dimers found in proteoglycans
proteoglycan function
crosslinking & cushioning/buffer between molecules
What are laminin and fibronectin?
Multiadhesive proteins: They have domains that act as binding sites for many different molecules. They are important in development because they form a cell substrate or highways for cells to migrate along.
