Cell-Cell Recognition and Adhesion Flashcards
what types of proteins mediate cell-cell adhesion?
transmembrane proteins
what are four different types of cell-cell adhesion transmembrane proteins?
- immunoglobulin super family (IgSF) - eg. N-CAM
- cadherins - eg. E-cadherin
- selectins - eg. P-selectin
- Integrins - eg. bind to IgSF proteins such as ICAM on the surface of endothelial cells
Define IgSF
family of cell surface proteins involved in cell-cell adhesion that are structurally related to the immunoglobulin subunits of antibody molecules
- characterized by well-organized loops
Describe homophilic interactions and heterophilic interactions between cells
homophilic interactions: cells with identical receptors on their surfaces interact with one another (cadherins and IgSF)
heterophilic interactions: cells with different receptors interact (selectins and integrins)
what was the founding member of the IgSF family called?
neural cell adhesion molecule (N-CAM)
How do cadherins stabilize their conformations?
Ca2+ binds to and stabilizes cadherins
(remember CAMs do not need calcium to bind)
Describe the E-cadherin:
what it looks like
how it interacts
the E-cadherin has 5 repeats on its extracellular domain through which two E-cadherin molecules can interact by “zipping together”
their cytosolic portions interact with the cytoskeleton
What is EMT (epithelial-mesenchymal transition)?
occurs in embryos and it is the breakdown of an epithelium into loosely organized, migratory cells
(this is accompanied by changes in cadherin expression)
What are the three main types of Selectins?
L-selectin on leukocytes
P-selectin on platelets
E-selectin on endothelial cells of blood vessels
Define selectins.
plasma membrane glycoprotein that mediates cell-cell adhesion by binding to specific carbohydrate groups located on the surface of target cells
Define lectins.
carbohydrate binding proteins which promote cell-cell adhesion by binding to a specific sugar or sequence or sugars exposed at the outer cell surface
What are the four blood types and what types of sugars are found at the end of each?
A: amino sugar N-acetylglycosamine is found at the end of the carbohydrate
B: the sugar galactose is at the end of the carbohydrate
AB: both sugars are present
O: neither sugar is present
