The Structural And Functional Diversity Of The Myosin Family Of Actinbased Molecular Motors

FOTH2 1 Departments of Molecular, Cellular and Developmental Biology, Cell Biology and Pathology, Yale University, New Haven, CT 06520 USA 2 School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, SINGAPORE 637551 Abstract In this chapter, a broad overview of the myosin family of actin-based motors with respect to diversity of myosin-domain structures and cellular functions will be outlined. It is meant as a backdrop for the more...

The Power Stroke

The position of the converter domain depends on whether the relay helix has a kink near its middle point or not. The kink in the relay helix occurs in the pre-power stroke state. The kink leads to a rotation of the converter domain through 60 . Removing the kink causes the lever arm to rotate back by 60 , which is very likely to be the elementary structural event in the power stroke. Conversely, creating the kink is the priming action necessary to reach the start of the power stroke. The outer...

References

M., Lowes, B. D., Minobe, W. A., Larrabee, P., Roden, R. L., Dutcher, D., Sederberg, J., Lindenfeld, J. A. and Wolfel, E. E. et al. (2002). Coordinate changes in Myosin heavy chain isoform gene expression are selectively associated with alterations in dilated cardiomyopathy phenotype. Molecular Medicine 8, 750-60. Agarkova, I. and Perriard, J. C. (2005). The M-band an elastic web that crosslinks thick filaments in the center of the sarcomere. Trends Cell Biol 15,...

Functional Diversity

Summarized below are examples of the broad range of functions ascribed to myosins thus far (see Table 1.1 for an overview). It is certain, particularly given the number of novel protein domains unearthed in ongoing genomic analyses, that the list will continue to expand both in size and in unexpected directions beyond our current traditional views of cytoskeletal functions. Table 1.1. Myosin functional diversity Function Tension generation Cell movement substrate Adhesion Endocytosis Clathrin...

Diversity Among Sarcomeric Myosins In Different Animal Species

Besides the specific molecular architecture which enables sarcomeric myosins to assemble into thick filaments and work together in the sarcomere structure, their second remarkable characteristic is the ability to respond to extremely different functional tasks. The molecular diversity of the members of the sarcomeric myosin family is the secret behind this essential feature. 5.2.1. Genes Coding for Myosin II are Present in All Living Organisms In the yeast Saccharomyces cerevisiae, at least 5...

Info

Schematic representation of primary structure of myosin I molecules. Skeletal muscle myosin II is also depicted for comparison purposes. Long-tailed class I myosins contain a motor domain with an ATP-binding site, ATP-sensitive actin-binding site and phosphorylation site. Following the motor domain is the IQ region. Light chains in the case of myosin II and calmodulin in the case of most myosins I bind to the IQ regions. Long-tailed class I myosins are subdivided into regions...

Cell Shape Membrane Dynamics

Cell Membrane Smooth Muscule

The roles of myosin VI in the cell and its possible involvement in a number of diseases disorders. The motor domain may be involved in transporting vesicles or protein complexes either as an array of monomers or dimers to specific cellular destinations and may also have anchoring functions to tether vesicles to actin filaments or cross-link actin filaments to membranes. The C-terminal targeting domain via specific adaptor proteins such as Dab2, GIPC, SAP97 and optineurin is involved...

Myosin Head Drawings

Coluccio (ed.), Myosins A Superfamily of Molecular Motors, 125-169. 2008 Springer. muscles. Once the complete genome sequence became available the inventory of myosins greatly expanded a large number of proteins containing the myosin motor domain has been discovered in eukaryotic cells, where they fulfill a variety of cellular functions from cell division to muscle contraction. Class-II (or conventional) myosins include not only the motor of skeletal-muscle contraction, but also (1) the...

Colour Plates

Combust Veis Fosseis

Schematic representation of traditional myosin classes including their known organismal distribution. This classification is based on phylogenetic analysis of the conserved myosin motor domains (see, e.g., Foth et al., 2006). The three groups as indicated on the right represent classes of myosins containing MyTH4 (and FERM) domains (group A), myosins containing DIL (dilute) domains and related classes (group B), and closely related classes II and XVIII (group C) (Foth et al., 2006)....

Variations In Myosin Body Plans

Most myosins have a basic body plan consisting of an N-terminal head or motor domain, a light chain-binding neck domain and a class-conserved, C-terminal tail domain with remarkable variations in domain organization among known myosin classes and newly characterized orphan myosins. The common view is that the tail-domain variations are critical for defining the functional properties of a given myosin. However, as noted in detail in Chapters 2 and 3, and summarized below, there are also...

Sarcomeric Myosin Isoforms Determine The Functional Properties Of Atrial And Ventricular Myocardium

Regional Expression in Atrium and Ventricle Species Diversity and Regulation of Expression In mammalian cardiac muscle only two MyHC isoforms are expressed, alpha-MyHC and beta-MyHC, the former being preferentially expressed in atrial myocardium and the second in ventricular myocardium. The relative proportion of alpha-MyHC and beta-MyHC changes across species and also during development within the same species Hoh et al., 1978 Schwartz et al., 1981 Mercadier et al., 1983 . In...

Biochemical And Mechanical Properties Of Class I Myosins

Steady and Transient State Kinetics Consistent with its membership in the myosin superfamily, class I myosins are actin-activated ATPases and therefore, interact with both actin and nucleotide. Myosins I whose kinetic properties have been studied include Acanthamoeba myosin-1A and -1B Ostap and Pollard, 1996a and vertebrate Myo1e El Mezgueldi et al., 2002 , which are in subclass 1 Myo1a Jontes et al., 1997 and Myo1b Coluccio and Geeves, 1999 Geeves et al., 2000 which are in subclass 2...

Mohammed Elmezgueldi And Clive R Bagshaw

Department of Biochemistry, University of Leicester, Leicester, LE1 9HN, UNITED KINGDOM Abstract Our understanding of the structure-function relationships in the myosin super family is largely based on studies of conventional myosin II isolated from striated muscle. The background to the elucidation of the mechanism of the actin-activated myosin II ATPase is described in detail and variations in kinetic properties within the myosin II class are discussed. This knowledge forms the basis upon...