Chapter 19 Flashcards
What are the two ways cells can communicate with each other
Directly or through the extracellular matrix
Network of proteins and polysaccharides that are secreted by the cell; directly bears mechanical stresses of tension and compression
Extracellular matrix
This junction allows neighboring cells to adhere together
Anchoring junctions
Seals gap between epithelial cells
Tight junction
Connects intermediate filaments in one cell to those in the next cell; provides mechanical strength; involves non classical cadherin proteins
Desmosome
Connects actin filament bundle in one cell with that in the next cell
Adherens junction
Anchors intermediate filament into cell to extracellular matrix
Hemidesmosome
Anchors actin filaments in cell to extracellular matrix
Actin linked cell matrix junction
Does not allow any passage of molecules between cell spaces; form barriers; usually formed between cells at the upper lateral surface
Tight junctions
Allow passage of molecules between neighboring cells
Gap junctions
These proteins are found in adherins and desmosome junctions( the anchoring junctions)
Cadherins
These proteins are found in hemidesmosomes and actin- linked cell matrix junction ( anchoring junctions)
Integrins
What are two types of cadherins
Classical
Non classical
What do cadherins need to perform the adhering function
Ca2+
Cadherins have _______ adhesion
Homophilic
They bind to cadherins if same or closely related subtype
What ions bind to hinge regions of cadherin domains; if these are absent what happens to cadherin structure
Ca2+
Collapses
These are adaptor proteins that aid in linking cadherins to actin filaments in adherens junction
Catenins
This binds when the alpha catenin has a conformational change due from tension
Vinculin bind to actin filaments and strengthens junction
This is composed of a long row of transmembrane homophilic adhesion proteins
Tight junction
What proteins are involved with tight junctions
Claudin
Occludin
What adaptor proteins are involved with tight junctions
Zona occludin
Multi domain proteins that allow many proteins to bind to generate the tight junction
Zona occludens
Allow transport of small water soluble molecules between neighboring cells
Gap junctions
What channel forming proteins compose the gap junctions
Connexins ( vertebrae)
Innexins ( invertebrates)
6 connexins polymerize to form
Hemi channel - connexon
Same connexins that form a comnexon
Homomeric
Different connexins that form a connexon
Heteromeric
Connexons that are homomeric and form a channel
Homotypic
For the connexons to have a homotypic and hetertypic channels what is significant about this characteristic
Allows for transport of variety of molecules
What are some cells that secrete ECM
Fibroblasts in connective tissues
These are highly charged polysaccharides that have a repeating disaccharide
GAGs
Aid I. Organizing the matrix and help in attaching cells to the matrix
Glycoproteins
Fibronectin
This protein is a dimer that are joined at c terminus with disulfide bonds ; can bind to collagen , integrins
Fibronectins
What is the degradation of the ECM mediated by
Matrix metallopeoteases > depend on Ca Zn for activity
Serine proteases
What links ECM to the cytoskeleton
Integrins
