MMT: structure and function of the ECM Flashcards
Name the 2 primary types of extracellular matrix
connective tissue and basal lamina
Describe connective tissue and its composition
space filling ECM. largely composed of various cells, fibrillar proteins, proteoglycans, and glycosaminoglycans
Describe the basal lamina and its composition
thin layer of assembled proteins that epithelial cells sit on top of. includes laminins, collagen 4, heparan sulfate proteoglycan, and nidogen
identify key structural entities in the procollagen molecule and specify the functional significance of these elements
It has a triple helical domain, and a cleaved N-propeptide and C-propeptide, and non-helical telopeptides. The helical domains cross link via non helical telopeptides being modified
What is the primary cell type that secretes fibrillar collagens and other ECM components
fibroblasts
Describe the role of proteoglycans in influencing collagen fibril assembly
Small leucine rich proteoglycans (SLRPS) facilitate the organization of fibrils head to tail, preventing their lateral interaction. One the length is correct, the fibrils can then grow in thickness
Describe the role of glycosaminoglycans in connective tissue
hydrate and lubricate tissue, shock absorption, and cell communication
describe the role of proteoglycans in the connective tissue
proteoglycans: they provide support and cushioning, they fill space to help the tissue maintain its integrity, and they can help regulate cell behavior
Describe the role fibronectin plays in ECM assembly and understand how force generation via the actin cytoskeleton facilitates fibronectin assembly.
Fibronectin in the extracellular space is connected on the cytoplasmic side to actin cytoskeleton via integrins. As the integrins move through the membrane, they unfold dimers of fibronectin fibrils. This forms unfolded linear fibronectin fibers, that create a network. this network further supports assembly the of ECM
Specify the primary extracellular matrix proteins that compose basement membranes.
Collagen, laminin, nidogen
describe the function of collagen in the ECM
not fiber forming, instead it is network forming
describe the role of laminin in the ECM
assembles into a network and is primary in contact with basal surface of the cells
describe the role of nidogen and heparan sulfate in the ECM
connect and stabilize collagen and laminin
briefly describe fibronectin
It is the master ECM protein; it can bind with other ECM proteins and organize the complex structure and help it bind with cells
Identify the proteins that self-assemble to form a sheet-like structure in the basement membrane
Collagen IV; they can assemble into dimers at the N terminal and tetramers at the C terminal; this gives them their network characteristic as opposed to being linear
