myosins

EVOLUTION: MYOSINS AND THE EARLIEST EUKARYOTES: "The myosins are a diverse group of motor proteins that move along the actin filaments that form a major component of the cell's internal scaffolding. Myosins are best known for powering muscle contraction, cell migration and cytokinesis (the separation of two daughter cells during cell division)[2,3]. These proteins typically consist of an amino-terminal motor domain that binds to the actin track and catalyses nucleotide hydrolysis -- the reaction used to harvest energy from ATP -- and a carboxy-terminal tail region. This directs the motor domain to targets within the cell, either binding to a cargo that is to be transported around the cell or anchoring the myosin to a particular site[2,3]."