"Myosin Superfamily M yosins are actin-dependent molecular motors that utilize the energy of ATP hydrolysis to generate force. The many functions of myosins include cell contractility, cell signaling, endocytosis, vesicle trafficking and protein/ RNA localization [Krendel and Mooseker, 2005; Woolner and Bement, 2009; Hartman and Spudich, 2012]. All myosins share certain structural and functional features, particularly the presence of an actin-binding head domain, which is also responsible for myosin ATPase activity. "
"Myosins participate in a variety of cellular processes, including cytokinesis , organellar transport, cell polarization, transcriptional regulation, intracellular transport, and signal transduction (Hofmann et al. 2009; Bloemink and Geeves 2011; Hartman et al. 2011). They bind to filamentous actin and produce physical forces by hydrolyzing ATP and converting chemical energy into mechanical force (Hartman and Spudich 2012). Both activities reside in the myosin head domain (PF00063). "
[Show abstract][Hide abstract] ABSTRACT: Myosins are key components of the eukaryotic cytoskeleton, providing motility for a broad diversity of cargoes. Therefore, understanding the origin and evolutionary history of myosin classes is crucial to address the evolution of eukaryote cell biology. Here, we revise the classification of myosins using an updated taxon sampling that includes newly or recently sequenced genomes and transcriptomes from key taxa. We performed a survey of eukaryotic genomes and phylogenetic analyses of the myosin gene family, reconstructing the myosin toolkit at different key nodes in the eukaryotic tree of life. We also identified the phylogenetic distribution of myosin diversity in terms of number of genes, associated protein domains and number of classes in each taxa. Our analyses show that new classes (i.e. paralogs) and domain architectures were continuously generated throughout eukaryote evolution, with a significant expansion of myosin abundance and domain architectural diversity at the stem of Holozoa, predating the origin of animal multicellularity. Indeed, single-celled holozoans have the most complex myosin complement among eukaryotes, with paralogs of most myosins previously considered animal-specific. We recover a dynamic evolutionary history, with several lineage-specific expansions (e.g. the 'myosin III-like' gene family diversification in choanoflagellates), convergence in protein domain architectures (e.g. fungal and animal chitin synthase myosins), and important secondary losses. Overall, our evolutionary scheme demonstrates that the ancestral eukaryote likely had a complex myosin repertoire that included six genes with different protein domain architectures. Finally, we provide an integrative and robust classification, useful for future genomic and functional studies on this crucial eukaryotic gene family.
Genome Biology and Evolution 01/2014; DOI:10.1093/gbe/evu013 · 4.53 Impact Factor
"Dynein interacts with several regulators, including three involved in most, if not all, of dynein's cellular functions: lissencephaly 1 (LIS1), nuclear distribution E (NUDE, of which there are two related genes, Nde1 and Ndel1, in mammals) and the dynactin complex (Fig. 2B) . Kinesins consist of a large superfamily  . The plusend-directed kinesins that drive endosome motility are mostly members of the kinesin-1, kinesin-2 and kinesin-3 families (Table 1; [12,14]). "
[Show abstract][Hide abstract] ABSTRACT: The endocytic pathway is essential for processes that define how cells interact with their environment, including receptor signalling, cell adhesion and migration, pathogen entry, membrane protein turnover and nutrient uptake. The spatial organisation of endocytic trafficking requires motor proteins that tether membranes or transport them along the actin and microtubule cytoskeletons. Microtubules, actin filaments and motor proteins also provide force to deform and assist in the scission of membranes, thereby facilitating endosomal sorting and the generation of transport intermediates.
Seminars in Cell and Developmental Biology 01/2014; · 5.97 Impact Factor
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