World of The Cell CH 15

Group of protein filaments that are the most stable components of the cytoskeleton of eukaryotic cells

Intermediate Filaments (IFs)

Member of a family of monomeric G proteins, which also includes Rac and Rho, that stimulate
formation of various actin-containing structures within cells

Cdc42

Member of a family of monomeric G proteins , which also includes Rho and Cdc42, that stimulate
formation of various actin-containing structures within cells.

Rac

Member of a family of monomeric G proteins , which also includes Rac and Cdc42, that stimulate
formation of various actin-containing structures within cells

Rho

Complex of actin-related proteins that allows actin monomers to polymerize as new branches
on the sides of existing microfilaments

Arp 2/3 Complex

Protein that binds to the end of an actin microfilament, thereby preventing the further
addition or loss of subunits

Capping Protein

Proteins that bind to actin microfilaments, thereby regulating the length or assembly of microfilaments or mediating their association with each other or with other cellular structures, such as
the plasma membrane

Actin Binding Proteins

Chemical compound derived from marine sponges that causes the depolymerization of actin filaments

Latrunculin A

Family of drugs produced by certain fungi that inhibit the a variety of cell movements by
preventing actin polymerization.

Cytochalasins

__1__ Principal protein of the microfilaments found in the cytoskeleton of nonmuscle cells and in the thin filaments of skeletal muscle; synthesized as a globular monomer __2__ that polymerizes into long
thin filaments __3__.

1) Actin
2) G-Actin
3) F-Actin

Proteins that stabilize the plus ends of microtubules,
decreasing the likelihood that microtubules will undergo catastrophic subunit loss

+-TIP Proteins

Any of the various accessory proteins that bind to microtubules and modulate their assembly, structure, and/or function

Microtubule-Associated Proteins (MAPs)

Structure that initiates the assembly of microtubules, the primary example being the centrosome

Microtubule-Organizing Center (MTOC)

Model for microtubule behavior that presumes two populations of microtubules, one is growing in length by continued polymerization at their plus ends and the other shrinking in length by
depolymerization.

Dynamic Instability Model

Drug that binds tightly to microtubules and stabilizes them, causing much of the free tubulin in the cell to assemble into microtubules

Taxol

Synthetic drug that inhibits microtubule assembly; frequently used instead of colchicine because
its effects are more readily reversible when the drug is removed

Nocodazole

Plant derived drug that binds to tubulin and prevents its polymerization into microtubules

Colchicine

Tubulin concentration at which the rate of assembly of tubulin subunits into a polymer is exactly balanced with the rate of disassembly.

Critical Concentration

Family of related proteins that form the main building blocks of microtubules.

Tubulin

Linear polymer of tubulin subunits; usually arranged in groups of 13 to form the wall of a microtubule

Protofilaments

Microtubules present in highly ordered bundles in the axonemes of eukaryotic cilia and flagella

Axonemal Microtubules

Microtubules arranged in loosely organized, dynamic networks in the cytoplasm of
eukaryotic cells

Cytoplasmic Microtubules

Polymer of the protein tubulin, with a diameter of about 25nm, that is an integral part of the
cytoskeleton and that contributes to the support, shape, and motility of eukaryotic cells; also found in eukaryotic cilia and flagella

Microtubules (MT)

Three dimensional, interconnected network of microtubules, microfilaments, and intermediate
filaments, that provides the structure to the cytoplasm of a eukaryotic cell and plays an important role in cell movement.

Cytoskeleton