Extracellular Matrix Interactions Flashcards
This family of proteins recognizes the ECM around cells and tells them if they belong where they are:
Integrins
What property of elastin provides its elasticity when a heart beat pumps blood into an elastic blood vessel?
Hydrophobicity and relaxed state beta-spirals & cross-linked network conformation.
Elastin cross-links derive from _______ and the aldehydes of lysine produced by lysyl osidase.
Lysines
Cross-links of elastin are called ________ and are derived from 4 _________ on up to 4 polypeptide chains.
Desmosines
Lysines
Desmosine requires _______ _______ to form.
lysyl oxidase
Fibronectin is a glycoprotein, T/F?
True
Fibronectin has an affinity for collagen, T/F?
True
Does fibronectin have an affinity for itself?
Yes
What does fibronectin do?
Mediates attachment of connective tissue proteins to each other.
Extracellular fibronectin is closely associated to which intracellular protein?
Actin
Does fibronectin bind heparin and heparin sulfate GAGs?
Yes
What three proteins/glycoproteins work together to anchor intracellular actin to extracellular collagen? Which one spans the plasma membrane of the cell?
Integrin, an adaptor protein (such as talin & vinculin) & fibronectin.
Integrin spans the PM of the cell.
Fibronectin binds to integrin, T/F?
True
Does fibronectin mediate ALL ECM attachments?
No. Laminin has similar functions
Describe the structure of integrin.
It is a dimer, made of two polypeptides: an alpha & beta subunit.
Integrins have a dual role. Describe this.
Anchoring ECM to intracellular framework and intracellular signaling.
How do the integrins know they are helping the cell attach to the proper ECM components?
There are different subgroups of integrins, specific for certain ligands.
Are integrins always active and ready to bind ligands in the ECM?
No. Extracellular signals can trigger integrin activation.
Leukocyte adhesion deficiency is caused by a lack of functional _______ on leukocyte cell surfaces.
Integrin
Glanzman’s Thrombasthenia is due to a lack of _______ on platelet cell surfaces that makes platelets unable to bind fibrin/collagen to form clots.
Integrin
In the case of the lamina propria, Type IV collagen binds to _______ , an integrin binding adaptor similar in function to fibronectin.
Laminin
The porosity (filtering capacity) of the lamina propria can be altered by increasing the number of out of phase (misaligned), stacked sheets of this network protein:
Collagen
Laminin has a distinct shape. Describe it.
Cruciform
