Cytoskeleton and Molecular Motors

Flashcards covering key vocabulary and concepts related to the cytoskeleton and molecular motors.

Cytoskeleton

A system of protein filaments providing structure and mechanical support to the cell.

Microtubules

A class of cytoskeletal fibers made of the protein tubulin.

Microfilaments

A class of cytoskeletal fibers made of the protein actin.

Intermediate Filaments

A family of proteins that are structurally different from microtubules and microfilaments; made of long, helical proteins woven together.

Polarized Filaments

Filaments with two different ends, a plus end and a minus end, exhibiting asymmetry in polymerization and depolymerization.

Plus End

The end of a polarized filament where monomers tend to be added.

Minus End

The end of a polarized filament where monomers tend to be lost.

Cortical Actin Network

Concentration of filamentous actin that underlies the plasma membrane and provides structural support.

G-actin

Globular actin, the soluble monomer form of actin.

F-actin

Filamentous actin, the polymerized form consisting of two strands of G-actin wound around each other in a helical structure.

Dynamic Instability

The general term for the turnover within filaments.

Treadmilling

A phenomenon in actin dynamics where the addition and subtraction of monomers occur at the same rate, maintaining filament length but with constant subunit turnover.

Arp2/3 complex

Facilitates initial polymerization of actin.

Thymosins

Monomer sequestering proteins that inhibit actin polymerization, leading to net depolymerization.

Tropomodulin

Protein that binds at the plus end of actin filaments and stabilizes it, preventing further monomer addition.

Profilin

Protein that interacts with actin filaments and accelerates the rate of monomer binding, promoting extension.

Cofilin

Protein which accelerates the rate of actin depolymerization.

Rho GTPases

A family of GTPases that regulate actin dynamics through molecular switch functions.

Stress Fibers

Parallel actin bundles generated by Rho activation, involved in adherence to a substrate.

Alpha and Beta Tubulin

Two tubulin proteins that form a heterodimer, the building block of microtubules.

Protofilament

A chain assembled with alpha and beta tubulin that compose microtubules.

GTP Cap

GTP bound tubulin added to keep adding tubulin monomers to extend microtubules.

Catastrophe

The rapid depolymerization of microtubules due to the loss of the GTP cap.

Rescue

Process where the GTP bound pool starts to add to the plus end of microtubules to prevents shrinkage and extend the microtubule again.

Kinesin 13

Protein that increases rate of loss of monomers from the microtubule.

Katanin

A protein that cuts microtubules in the middle.

Microtubule organizing center (MTOC)

A protein machine that controls the nucleation of microtubules.

Centrosome

Animal cells' microtubule organizing center.

Gamma Tubulin

Tubulin that is contained in nucleating sites within the centrosome matrix.

Molecular Motors

Proteins that effect directional motion.

Myosins

Molecular motors associated with actin that move from minus to plus.

Kinesins

Microtubule motors that walk from minus to plus aiding in cell movement from cell body closer to the periphery.

Nuclear Lamins

Intermediate filaments that provide mechanical strength and structure to the nuclear membrane.

Vimentin Family

Intermediate filaments mainly in cells of mesenchymal origin.

Neurofilament Proteins

Intermediate filaments that help support the long processes of axons.

Cytochalasins

Proteins that bind to the ends of actin filaments, stabilizing them.