Cytoskeleton and Extracellular Matrix

Fill-in-the-blank flashcards covering key concepts from the Cytoskeleton and Extracellular Matrix lecture notes.

There are three types of cytoskeletal protein filaments: __, microtubules, and intermediate filaments.

Actin filaments

Actin polymerization is facilitated with __ hydrolysis and occurs more rapidly at the barbed end than at the pointed end.

ATP

Treadmilling is the continuous addition of actin at the __ end while dissociation occurs at the pointed end.

barbed

Cytochalasin binds the actin filament at the __ end, blocking elongation.

barbed

Phalloidins bind to actin filaments and prevent actin __.

dissociation

Formin: binds ATP-actin and starts __ and adds actin to the barbed end.

nucleation

Profilin: works with formin to exchange ADP for __ on actin.

ATP

Arp2/3 initiates the growth of __ actin filaments.

branched

WASP protein promotes actin polymerization at the leading edge by stimulating __.

Arp2/3

Wiskott-Aldrich syndrome is caused by a mutation in the gene __ on the X chromosome.

WAS

Cofilin cleaves the actin filament, allowing remodeling by new free __ ends.

barbed

Dystrophin interacts with actin and connects the cytoskeleton to the extracellular matrix in __ cells.

muscle

Hypertrophic cardiomyopathy most commonly involves mutations in the gene encoding __ heavy chain.

myosin

Fibroblasts attach to the ECM by the transmembrane proteins called __ at focal adhesions.

integrins

The actin cytoskeleton at adherens junctions connects cells to other cells through __ and catenins.

cadherins

Microvilli contain actin-binding protein __, which bundles actin filaments.

fimbrin

Myosin I moves along an actin filament by the hydrolysis of __.

ATP

Myosin V functions as a __ to transport cargo along actin filaments.

dimer

GTP hydrolysis weakens the affinity of tubulin at the __ end.

minus

The chemotherapeutic drug __ stabilizes microtubules.

Taxol

MAPs include polymerases that accelerate growth at the plus end and __ to promote shrinkage.

depolymerases

Kinesin I moves toward the microtubule __ end.

plus

Cilia and flagella have an axoneme with a '' arrangement.

9+2

Basal body is the minus end of a cilium anchored in a centriole with nine __ of microtubules.

triplets

Intermediate filaments are apolar and provide mechanical strength; examples include keratins, vimentin, neurofilaments, and __.

nuclear lamins

Desmosomes link intermediate filaments to neighboring cells via desmosomal cadherins and __.

plakoglobin

Epidermolysis bullosa simplex (EBS) is caused by a mutation in __ genes.

keratin

There are approximately __ types of collagen.

40

The __ residues are formed in a vitamin C-dependent enzymatic reaction.

hydroxyproline

Osteogenesis imperfecta involves mutations in COL1A1 or COL1A2 encoding type __ collagen.

I

Vascular type of Ehlers-Danlos syndrome is caused by a mutation in COL3A1 encoding type __ collagen.

III

Basal lamina consists of type __ collagen.

IV

Fibrillin-1 is embedded in elastin fibers and sequesters __ (signaling molecule).

TGF-β

Marfan syndrome is caused by mutations in the gene __ encoding fibrillin-1.

FBN1

Glycosaminoglycans (GAGs) are sulfated and negatively charged except __.

hyaluronan

Aggrecan is found in cartilage and consists of hundreds of chains of __ attached to a core protein.

chondroitin sulfate

Fibronectin has binding sites for both __ and proteoglycans.

collagen

Laminin is a T-shaped heterodimer that binds to cell surface receptors called __.

integrins

Laminin association with __ connects it to collagen.

nidogen

At focal adhesions, the beta-subunit of integrins associates with the actin cytoskeleton with proteins such as __, vinculin, and α-actinin.

talin

Hemidesmosomes connect epithelial cells to the ECM via integrin α6β4 and are linked to intermediate filaments through __.

plectin

Non-syndromic deafness can be caused by variants in the gene __, which encodes connexin 26.

GJB2

There are three common types of selectins: L-selectin, E-selectin, and __.

P-selectin

Integrins are transmembrane proteins with two subunits (α and β) with binding sites for ECM components and exist in inactive and active __.

conformations

Cadherins mediate cell-cell adhesion and link to the actin cytoskeleton through __ (β-catenin is an example).

catenins

Gap junctions are formed by proteins from the __ family.

connexins