Exam 3 Flashcards
What is the subunits of cell-cell junctions?
intermediate filaments
Structure of an intermediate filament?
long alpha helical region with sticky ends, 8 come together antiparallelly
Most apical to most basal cell-cell junctions
Tight junctions, adherin, desmosomes, gap junctions
What is the purpose of tight junctions?
They form tight seals, press membranes close together
What are Claudins and occludins?
Multi-pass transmembrane proteins, interact with other, the extracellular domains are wide and short which allows for Z0 scaffolding proteins to bring each other into close proximity
What are Gap junctions?
Gap junctions connect the cytoplasm of neighboring cells
What in gap junctions allows for connection of cytoplasms?
Connexins, 6 line up and create a membrane channel
What do Gap junctions membrane channels allow to pass?
ions, ATP, not proteins
What do classical adherin domains form?
Adherins junctions
How do Cadherins work in cell-cell interactions?
Cadherins have a short C-terminus domain that interacts with catenin inside the cell (adapter protein) the long extracellular domain interacts with cadherins from other cells, they bunch together,
What do Cadherin domains rely on the presence of?
They rely on high concentrations of extracellular Ca2+
What is homotypic binding?
domains are specifically structured to recognize and bind to cadherins of the same type on neighboring cells. For example, E-cadherin on one cell interacts exclusively with E-cadherin on another cell.
What would happen if there were high vs. low cadherin levels?
Cells with higher levels of cadherin expression form stronger and more extensive adherens junctions, creating robust connections that surround the cell entirely. Conversely, cells with lower levels of cadherin form weaker, more sporadic junctions, particularly at the edges.
What is mechanotransduction?
Mechan transduction is when mechanical forces alter behavior of the cell
How does Mechano-transduction apply to cadherins junctions?
MORE
When tension is applied to the cell, the cadherins junctions, alpha catenin is recruited by Beta catenin,
What happens when tension is applied to Cadherins junctions?
The beta subunit and alpha subunit interact, the alpha subunit is stretched and opens binding sites for vinculin which recruits more actin
Whar are desmosomes?
Cadherin base junctions that connect to intermediate filaments.
What are Desmoglein and desmocollin?
are nonclassical cadherins. Their cytoplasmic tails bind plakoglobin (γ-catenin) and plakophilin (a distant relative of p120-catenin), which in turn bind to desmoplakin. Desmoplakin binds to the sides of intermediate filaments, thereby tying the desmosome to these filaments.
How do integrins relate to cell-cell junctions?
heterodimers with alpha and beta subunits, they have short c terminus ends and long N terminus ends in which bind to specific amino acid sequence motifs in extracellular matrix proteins or, in some cases, in proteins on the surfaces of other cells.
What are hemidesmosomes?
anchor intermediate filaments to the matrix,
How is collagen 17 involved in hemidesmosomes?
Hemidesmosomes have collagen 17 which anchors them to the extracellular matrix, interacts with the extracellular matrix (ECM) components, such as laminin-332 and collagen IV, to stabilize the connection between cells and the ECM
