InterPro domain: IPR004009

Members of the myosin superfamily of actin-based motors act in a variety ofcellular functions such as muscle contraction, cell and organelle movement,membrane trafficking, and signal transduction. Although myosin motor domains show a high degree of sequence conservation, the individualmyosin classes are clearly defined by differences in the head structure. TheN-terminal region of myosins from different classes varies greatly in lengthand amino acid composition among the individual members. Many myosins have anSH3-like domain at the N terminus of the motor domain. This includes myosinsin classes II, V, VI, XI, XXII and XXIV. The myosin N-terminal SH3-like domainmay mediate some aspect of the conformational communication that occurs withinthe myosin head during actin and nucleotide binding. Part of this effect maybe mediated through interactions with the neck-associated essential lightchains that are in close proximity to this portion of the head domain and alsotransiently interact with actin [ 1 , 2 , 3 ].

The myosin N-terminal SH3-like domain comprises ~50 amino acids and forms aprotruding, six-stranded, antiparallel, beta-barrel domainwith similarities to the SH3 domain [ 4 , 4 ].

1. Functional characterization of the N-terminal region of myosin-2. J. Biol. Chem. 281, 36102-9
2. Evidence for an interaction between the SH3 domain and the N-terminal extension of the essential light chain in class II myosins. J. Mol. Biol. 371, 902-13
3. Myosin diversity in the diatom Phaeodactylum tricornutum. Cytoskeleton (Hoboken) 67, 142-51
4. The structure of the myosin VI motor reveals the mechanism of directionality reversal. Nature 435, 779-85