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What is the ECM ?
The stuff outside the cell
What are the roles of the ECM ?
To provide an attachment point for cells
What is the basic composition of the ECM ?
Gel like substances and fibrous type substances
What is the role of proteins in the ECM ?
To provide strength and fibrous strength for the ECM
What is the role of polysaccharides in the ECM ?
Trap water in the sugar so it can swell up into a gel like state
Where and how proteins and polysaccharides are produced in the ECM ?
Created by cells secreting and making their own Extra Cellular Space
What is collagen and it’s basic structure ?
Collagen is the main protein of the ECM and is a triple Helacy structure
What is the role of the post translational modification in collagen ?
We add an OH, but there is a cleavage point
What are proteoglycans ?
Proteins that have a sugar attached to them
We’re are proteoglycans made ?
THE ECM
What is the basic composition of proteoglycans when using an example of aggrecans ?
It consists of a relatively small sugar with multiple disaccharides attached to it. The protein is then attached to a long polysaccharide, making a very large molecule that is mostly sugar.
What are disaccharides ?
They are sugars that consist of two carbohydrate rings (di = 2). Glucose is a monosaccharide. Two glucose molecules put together are considered a disaccharide.
What is fibronectin and it’s structure ?
It’s considered the glue of the ECM and is a quatinary structure
What protein forms dimers ?
Fibronectin
What contains various binding domains ?
Dimers
What will alternative splicing do to fibronectin ?
Creates multiple fibronectin proteins
How does Fibronectin connect cells to the ECM ?
Fibronectin has three binding domains (collagen binding domain, polysaccharide binding domain, and cell binding domain). By binding those three things, it holds the main components of the extracellular matrix together.
What is integrin, its basic structure and how does it link to the cytoskeleton ?
Integrin is a transmembrane protein that has an intracellular domain that binds to the cytoskeleton, a transmembrane domain that passes through the membrane, and a fibronectin binding domain that binds to fibronectin. Because fibronectin binds the components of the ECM, integrin links the cytoskeleton (inside the cell) to the ECM (outside the cell
What are the three different types of cell junctions ?
Adhesion, tight and Gap junctions
Describe an Adhesion junction ?
Adhesion junctions are strong, hold cells together, tied directly to the cytoskeleton
Describe tight junctions
Tight junctions are not strong, can be linked to cytoskeleton to hold in place, but provide seal so things can’t pass between cells
Describe Gap junctions
They are known as communicating junctions. Acoomadte the transfer of small molecules between neighboring or joint cells. They’re made up of connexins that assemble into these channels
What are example of where the three different types of junctions exist ?
-Adhesion is tied directly to cytoskeleton -Tight is linked to the cytoskeleton -Gap transfers molecules between neighboring cells
What are heterophilic interactions ?
Two different proteins that interact with each other