Cytoskeleton, ECM, Cell-Cell adhesions Flashcards
Microfilaments, Microtubules, Intermediate Filaments, Junctions, proteins involved in ECM
What are the components of the extracellular matrix?
Microtubules, Intermediate Filaments, Actin filaments (microfilaments)
Describe Microtubules
Microtubules are the largest in diameter, 25 nm. They are hollow and rigid, made up of Alpha and beta tubulin dimers. Structured spirals of dimers are added to the + end/
Describe Intermediate Filaments
Medium size, 10-12 nm. Extremely stable, and flexible, can stretch up to 2x. In humans there are 6 classes of genes for IFs, an important one is Keratin. IF’s are non polar and often associate with membrane proteins, allowing them to link cells within tissues, or to ECM. Desmosomes + Hemidesmosomes.
Describe Microfilaments (Actin Filaments)
Built of G-actin monomers that bind ATP, grows from + (barbed) end. The result is a two stranded F-actin. MFs play roles in whole cell motility, intracellular motility, and cell shape.
What is the ECM?
An organized network of secreted molecules that provides scaffolding to the cells and tissues. Additionally provides physical, biochemical and mechanical signals that play key regulatory roles in determining cell shape and activities. Made up of the Epidermis, Basement membrane, and the Dermis
What is the basement membrane?
AKA basal lamina, a continuous sheet of 50 to 200 nm thick that surrounds nerve fibers, muscles and fat cells. The BM underlies the basal surface of epithelial cells (such as epidermis of skin). Also underlies the endothelial lining of blood vesles.
What are the 3 components of the ECM?
Collagen
Proteoglycans
Linker Molecules -Laminin and Fibronectin
What is Collagen and its functions?
Collagen is the most abundant protein in the human body. Collagen is produced by fibroblasts smooth muscle and epithelial cells. there are 28 different types. Type 1 aligns itself in staggered rows. Type IV is nonfibril, and restricted to the basement membrane where it provides mechanical support.
What are proteoglycans and their functions?
protein-polysaccharide complex, with a
core protein attached to
glycosaminoglycans (GAGs). Negative charges on the sulfated GAGs, attract cations, which in turn
bind large numbers of water molecules. As a result, proteoglycans form a porous, hydrated gel that fills the ECM to resist crushing.
What are Linker Molecules?
there are many types, they have multiple binding sites for ECM components and cell surface. Laminin and Fibronectin.
What is Laminin?
Laminin is a family of 15 glycoproteins, made up of 3 polypeptide chains. Looks like a cross with 3 short arms and one long arm. they can greatly influence a cells potential for migration, growth and differentiation.
What do Laminin and fibronectin play a role in the migration of?
Primordial germ and neural crest cells. Laminin is required for this process
What are Integrins?
about 24 different types, exist on the surface of cells. They bind ECM by RGD motif. They can exist in an active (upright) or inactive (bent) state. They play a role in anchoring a cell to its substrate. They also play a role in signaling (focal adhesion)
What are the types of Intercellular junction complexes?
Adherens junction - link neighboring cells and connect to actin filaments in the cytoplasm.
Gap Junction - links cells together and connects to cytoplasmic intermediate filaments.
Tight junction - a barrier that limits diffusion of ions and solutes between the cells and molecules of the Plasma membrane domains
Desmosome - links cells together and to cytoplasmic IFs
Hemidesmosomes - Link cytoplasmic IFs to the basal lamina across the PM
