V. Plasmalemma-Cytoskeleton Interaction
The plasma membrane is stabilized and shaped by its association with the internal cytoskeleton, primarily through integrin proteins.
- Association in Red Blood Cells
The cytoskeleton provides structural reinforcement to the red blood cell membrane.
- Spectrin: A long, flexible protein composed of α and β chains that form tetramers, creating a scaffold.
- Actin: Attaches to spectrin tetramers to form a latticework.
- Band 4.1 Protein: Binds to and stabilizes spectrin-actin complexes.
- Ankyrin: Links the spectrin-actin complex to the transmembrane band 3 proteins (a type of integrin).
- Association in Nonerythroid Cells
A similar principle of linkage applies in other cell types.
- Actin Filaments form a meshwork cross-linked by α-actinin.
- Vinculin binds to α-actinin and to another protein, talin.
- Talin in turn attaches to an integrin in the plasma membrane, completing the link.