Lecture #13 Flashcards
________ are a family of membrane proteins unique to animals. It is composed of two membrane-spanning polypeptide chains, an α chain and a β chain (heterodimer).
Integrins
The _____ conformation of integrin corresponds to its inactive state, Integrins with a bound ligand (eg-talin, a-actinin) are found in an _______ conformation.
bent, upright
_______ integrins become clustered –> strengthens the cell-ECM interactions.
Activated
Integrins have two major activities:
1) ______ of cells to ECM (or to other cells) and
2) ________ of signals between the external environment and the cell interior.
adhesion, transmission
Integrins have two signaling mechanisms: ?
Inside-out
Outside-in
_______-___: The binding of intracellular proteins to integrins (such as talin) induces a separation of the two integrins subunits and conversion to their active conformation (from inside toward outside).
Inside-out
_______-___: The binding of extracellular ECM components to integrins can also induce a conformational change at the opposite, cytoplasmic end of the integrin. Changes at the cytoplasmic end can, in turn, alter the way the integrin interacts with a host of different cytoplasmic proteins, modifying their activity (from outside toward inside).
Outside-in
Outside-in signals can induce a _________ change in talin
conformational
Outside-in signals transmitted by _______ can influence cell differentiation, motility, growth, and cell survival.
integrins
Most malignant cells can grow in liquid suspension –> integrin-__________
independent
Fibronectin, laminin, and proteoglycans bind Integrins through the RGD ? (arginine-glycine-aspartic acid)
amino acid sequence
The integrin-ECM interaction through the RGD can be targeted to prevent _____ _____ or _______
heart attack, stroke
Cultured cells are anchored to the surface of the dish only at scattered, discrete sites, called _____ ________
focal adhesions
Focal adhesions play a key role in cell _______ and locomotion (muscle & tendons) and are ________ structures.
adhesion, dynamic
Focal adhesion linkage to cytoskeleton is mediated by ____ binding proteins: talin, a-actinin, vinculin
actin
Focal adhesions create ________ forces or respond to such forces from the environment. _____ filaments are the source of these forces.
mechanical, Actin
_______ cell adhering on fibronectin-coated flexible posts: focal adhesions deflect posts due to force exertion
Fibroblast
Cell-ECM attachment in vivo is seen at the basal surface of _______ ____, anchored to the underlying basement membrane.
epithelial cells
_____________ contain a dense cytoplasmic plaque with keratin filaments
Hemidesmosomes
