Cell Junctions, Adhesion Molecules, and Extracellular Matrix Flashcards
What are the calcium dependent CAMs?
cadherins
selectins
What are the non calcium dependent CAMs?
integrins
immunoglobulin superfamily molecules
What ligands do cadherins recognize?
other cadherins (same or different)
What ligands do selections recognize?
carbonhydrates
What ligands do integrins recognize?
extracellular matrix molecules
What ligands do Ig superfamily recognize?
integrins
What stable types of junctions do cadherins have?
occludens and desmosomes
What stable types of junctions do selectins and Ig superfamily have?
none
What types of stable type junctions do integrins have?
hemidesmosomes
Describe classical cadherins
major components in calcium mediated adherent junctions
typically form cis and trans homophilic dimers
What are the three types of classical cadherins?
E-cadherins
N-cadherins
P- cadherins
Where are e-cadherins found?
epithelial tissues and brain
Where are n-cadherins found?
nerve cells, muscle cells, fibroblasts, lens cells
Where are p-cadherins found?
placenta and epidermis
Describe non classical cadherins
include desmocollins and desmogleins
found in desmosomes (macula adherins)
Extracellular portion contains multiple copies of _______
cadherin domain motif
Intracellular portion of cadherin superfamily are varied, thus able to interact with different _______ and components that anchor the ________ to cytoskeleton
intracellular ligands; cadherin; cytoskeleton
binding between cadherins is generally _____
homophilic
homophilic binding occurs at the _______ tips of the cadherin molecules
n- terminal
Extracellular portion of cadherin consists of several copies fo a motif called a ______
cadherin domain
_____ ions bind to sites near each hinge and prevent it from flexing, so cadherin domain is rigid rod
Ca2+
When Ca2+ is removed from a cadherin domain, what happens?
hinges can flex, and structure becomes floppy. Conformation at N terminus changes, weakening the binding affinity and disrupting the adhesion
cadherins are then degraded
Cadherins typically bind to their partners with relatively _____ affinity
low
In a cadherin mediated adhesion how to strong attachments form?
formation of many weak bonds in parallel
What is sorting out?
cadherin dependent homophile adhesions mediate highly selective recognition, enabling cells of a similar type to stick together and to stay segregated from other types of cells
Appearance and disappearance of cadherins correlate with major _____ in which tissues ______
morphogenetic events, segregate from one another
What does the intracellular domain do for cytoskeleton filaments?
provide anchorage