Last unit Flashcards
_____ _______ occurs whenever cells touch appropriate substrata
cell adhesion
In epithelia, cells form specialized, morphologically distinct devices called _______ ________
intercellular junctions
Four major classes of molecules in the ECF
- glycosaminoglycans (GAGs), usually linked covalently to proteins to form proteoglycans;
- fibrous proteins, such as collagen and elastin;
- multidomain adapter proteins, such as fibronectin and laminin;
- water and many solutes.
glycosaminoglycans (GAGs) are usually linked covalently to proteins to form _________
proteoglycans
elastin and collagen are examples of
fibrous proteins
Fibronectin and laminin are examples of
multidomain adapter protiens
The proteoglycan molecules form a highly ________ ___ in which the fibrous and multidomain proteins are embedded
hydrated gel
Two of the basal lamina’s characteristic components are:
collagen IV and laminin
GAGs consist of unbranched ________ chains composed of ________ repeats.
polysaccharide, disaccharide
Sulfation and carboxyl groups convey to the GAGs a high negative charge and, thus, the capacity to become _____ ______
highly hydrated
Glucosamines typically bind to specific proteins, with the exception of ______ ______
hylaluronic acid
purposes of GAGs
- create hydrogel in ECM
- Maintain gradients of different signaling morphogens
- Cell adhesion
- Preventing liquid leakage between high and low pressure environments
proteoglycans are covalently linked complexes of _____ and _______, typically of very high molecular weight.
GAGs and protein
_____ ______ are the most abundant proteins in mammals (about 25% of protein mass)
fibrous proteins
Which type of collagen is the most common form, abundant in connective tissues?
Collagen I
Which type of collagen is characteristic of the basal lamina
Collagen IV
Fibronectin
Component of ECM:large, dimeric glycoprotein whose two large subunits are linked together by disulfide bonds. Each subunit is folded into a series of functionally distinct binding domains.
Laminin
very large protein, composed of three subunits (α,β,γ) that form an asymmetric, disulfide-linked cross with the longer arm formed by a helical structure containing long stretches of all three subunits. Laminin is found in the basal lamina only (hence its name).
Cadherins
single-pass transmembrane glycoproteins that operate as homodimers. They are very common in intercellular junctional complexes. Must be anchored to actin cytoskeleton
Integrins
These are the “classic” adhesion molecules interacting with the ECM. Thus, their binding is heterophilic. Integrins are composed of α/β heterodimers. Many different α and β sub-units exist (both are transmembrane glycoproteins). They are mixed and matched to some degree.
What accounts for the large variety of integrins?
Since both subunits participate in ligand binding, this results in a large variety of integrins with distinct binding selectivities
CAMs
proteins located on the cell surface involved in binding with other cells or with (ECM) in cell adhesion.
Structure of CAMs
an intracellular domain that interacts with the cytoskeleton, a transmembrane domain, and an extracellular IgG like domain that interacts with other CAMs
Signaling molecules can be ________ by cell-cell adhesion
activated