Skip to content
Login Register

#plus end

2 public questions tagged with this topic.

Cytoskeleton

In microtubule polymerization, which end exhibits faster growth?

Polarity of microtubules dictates directionality of transport and regulation by plus end tracking proteins +TIP network. Lattice assembled from head to tail alpha beta dimers creates structurally distinct ends with different chemistry. Minus end shows alpha tubulin outward typically embedded in gamma TuRC within MTOC exchange slow often capped by patronins CAMSAP family. Plus end exposes beta tubulin with GTP binding pocket capable of rapid subunit addition with on rate about 7 per micromolar per second versus minus about half. In vitro growth rates show plus about two to three fold faster elo

Ref: Alberts et al., Molecular Biology of the Cell, Chapter 14 – Plus end exhibits faster growth due to polarity.

View Details
Cytoskeleton

The rate of ATP-actin addition is __ times faster at the (+) end compared to the (-) end.

Elongation kinetics at filament ends measured using TIRF microscopy of single filaments and pyrene actin assembly shows strong asymmetry. Barbed plus end characterized by high on rate constant 11.6 per micromolar per second and off rate 1.4 per second, critical concentration 0.12 micromolar, while pointed minus end on rate 1.3 per micromolar per second off rate 0.8 per second Cc 0.6 micromolar. Ratio on rates roughly nine fold, often approximated as ten fold faster at plus end for ATP actin at physiological ionic strength 50 millimolar KCl 1 millimolar MgCl2. ATP actin cap at plus end stabiliz

Ref: Pollard and Earnshaw, Cell Biology, Chapter 12: Barbed End Kinetics and Actin Polarity.

View Details