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Intercellular Junct.
WVSOM Class of 2012 Intercellular Junctions
Question | Answer |
---|---|
Numerous different linking proteins tie the membranes of adjacent epithelial cells closely together around their apical perimeters. What are these called? | tight junctions |
tight junctions are also called what? | zoneal occludens |
what are bound by 2 adaptor proteins and cadherins? | belt desmosome |
multiple belt desmosomes anchor what? | circumferential belt |
Constriction of these microfilaments around the “necks” of these cells pull them into a bottleneck shape: | circumferential belt |
transmembrane complexes allowing diffusion of small molecules between cells are what? | gap junctions |
isolated “spot welds” joining two cells at their lateral surfaces; serve to tie together the cytoskeletons of multiple cells across a tissue. what are these structures? | spot desmosomes |
Complexes that anchor epithelial cells to the extracellular matrix of the basal lamina are what? | hemidesmosomes |
structures that anchor microfilament stress fibers to the basal surface of fibroblasts and cancer cells which have attached to the substratum are what structures? | focal adhesions |
what is a heterodimeric, transmembrane protein that binds a number of factors on both sides of the membrane? | integrin |
these junctions seal epithelial layers against diffusion by preventing molecules from passing between the cells: | tight junctions |
tight junctions also block passage of what? | components of the plasma membrane (lipids, proteins) between the apical and basal regions of epithelial cells |
gap junctions have how many polypeptides per junction? what shape are they? | 12; hexagonal |
what are some examples of molecules that pass through gap junctions? | calcium for muscles, ions for nerves, camp for many tissues |
belt desmosomes are also called what? | adherens junctions |
these link the microfilament cytoskeleton of one cell with that of another cell: | belt desmosomes |
which desmosome is most like a focal adhesion? | belt desmosome |
belt desmosomes anchor what fibers to the membrane? | microfilaments |
in belt desmosomes, the filaments are linked to the same adaptor proteins used in what other junction? | focal adhesions |
what are a family of calcium dependant transmembrane glycoproteins, often required for tissue specific cell-cell binding during development? | cadherins |
belt desmosomes are linked by what? | cadherins |
what are microfilament bundles attached to belt desmosomes, which encircle the apical perimeter of epithelial cells just below the tight junctions? | circumferential belt |
what is an autoimmune disorder that attacks one of the transmembrane linker proteins in spot desmosomes? | pemphigus vulgaris |
in hemidesmosomes, on the cytoplasmic side, intermediate filaments are bound to a pair of plaques consisting of what? | adaptor proteins |
adaptor proteins in hemidesmosomes are held to the plasma membrane by integrin, which is tied to what? | laminin in the basal lamina |
integrin is also used in focal adhesions where it links what to what? | microfilaments to fibronectin |
in focal adhesions, on the outer side of the membrane, integrin binds what to link the cytoskeleton with the extracellular matrix? | fibronectin |