Brain myosin-V is a two-headed unconventional myosin with motor activity

TLDR

Chicken myosin‑V is a recently recognized class of myosins distinct from myosins‑I and –II, consisting of two heads linked by a ~30 nm stalk ending in a globular region of unknown function. The study reports purification, electron‑microscopic visualization, and motor characterization of this myosin‑V protein. The authors purified the protein, visualized it by electron microscopy, and examined its motor properties. Myosin‑V binds and decorates F‑actin, exhibits actin‑activated Mg‑ATPase activity, moves actin filaments toward barbed ends at up to 400 nm/s, does not form filaments, and each heavy chain associates with ~four calmodulin light chains and two smaller proteins of 23 and 17 kDa.

Abstract

Chicken myosin-V is a member of a recently recognized class of myosins distinct from both the myosins-I and the myosins-II. We report here the purification, electron microscopic visualization, and motor properties of a protein of this class. Myosin-V molecules consist of two heads attached to an approximately 30 nm stalk that ends in a globular region of unknown function. Myosin-V binds to and decorates F-actin, has actin-activated magnesium-ATPase activity, and is a barbed-end-directed motor capable of moving actin filaments at rates of up to 400 nm/s. Myosin-V does not form filaments. Each myosin-V heavy chain is associated with approximately four calmodulin light chains as well as two less abundant proteins of 23 and 17 kd.