Cell Biology: Discuss the importance of membrane proteins, including examples of notable membrane proteins, how proteins affect membrane characteristics, and how these proteins are involved in cellular protection and signaling

What is spectrin?

A protein found in RBCs that support the membrane and provide shape.

A patient comes in for blood work and they find that their RBC are abnormally shaped? What might they have? Why is this bad?

A spectrin deficiency (spherocytosis) This means that the membranes are not stable and will cause the RBC to rupture (anemia). Jauncice can also occur due to the rupture and phagocytosis because bilirubin is released each time.

What are crucial structures needed on the cell surface for cell recognition and adhesion?

Surface carbohydrates.

A cell experiences mechanical changes that ultimately destroys the membrane. What might this cell be lacking and why is this important?

The cell does not have glycocalyx. It is a sugar coating on the outside of the membrane that protects it from mechanical changes and can also attract water and allows certain things to squeeze through. Without this layer, the cell is unprotected.

How do proteins affect the cell membrane?

The support the thin cell membrane, they can localize bilayer areas to form membrane domains, and they aid in permeability via transporters and channels.

What are lectins? Provide a clinical correlate where these are important.

Transmembrane proteins that line blood vessels that bind to oligosaccharides. Neutrophils contain surface sugars that are recognized by lectin allowing adhesion and migration of tissues.

What are the different types of membrane proteins and describe what they look like?

Transmembrane: amphipathic that extend through the bilayer Monolayer: Entirely with the cytosol associated with an a-helix within the membrane. Lipid-linked: Lies outside the bilayer attached via lipids. Protein attached: Linked to proteins in the bilayer.

What are common types of transmembrane proteins?

Transporters, anchors, receptors, and enzymes