SPECIALIZATIONS OF THE APICAL CELL SURFACE Flashcards
examples of specializations
Microvilli
Stereocilia
Cilia
what does the thick glycocalyx (G) covering microvilli of the intestinal brush border includes
membrane-bound proteins and enzymes for digestion of certain macromolecules
Each microvillus contains bundled actin filaments capped and bound to the surrounding plasma membrane by
actin-binding proteins such as espin, fascin, villin, and fimbrin
what do the plus and minus ends of the actin filaments attached to
plus- amorphous region, composed mostly of villin
minus- embedded in and attached to the terminal web
what is the terminal web
complex of actin, spectrin and intermediate filaments at the cortex of epithelial cells
what connects the peripheral members of the actin filaments to the plasma membrane of the microvillus (for support)
myosin-I and calmodulin
what is located in the terminal web and binds actin each other in microvilli
tropomyosin and myosin II
where are sterocilia found
on the absorptive epithelial cells lining the male reproductive system
where do sterocilia hold a motion-detecting function
inner ear sensory cells
what are the actin filaments in stereocilia held together by
fimbrin
true or false, sterocilia is motile
false
what do ezrin (villin-2) do
attach the peripheral-most members of the actin filament bundle to the cell membrane of the stereocilia
there is no _____ at the tip of the stereocilia where the _______ of the actin filaments ______
villin
plus ends
terminate
where do the minus ends of the actin filaments terminate
in the terminal web
what are the three types of cilia
- motile cilia
- primary cilia
- nodal cilia
