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Unlike processive cellular motors such as myosin V, whose structure has recently been determined in a "rigor-like" conformation, myosin II from contracting muscle filaments necessarily spends most of its time detached from actin. By using squid and sea scallop sources, however, we have now obtained similar rigor-like atomic structures for muscle myosin(More)
Myosin V is the best characterized vesicle transporter in vertebrates, but it has been unknown as to whether all members of the myosin V family share a common, evolutionarily conserved mechanism of action. Here we show that myosin V from Drosophila has a strikingly different motor mechanism from that of vertebrate myosin Va, and it is a nonprocessive,(More)
The LC8 family members of dynein light chains (DYNLL1 and DYNLL2 in vertebrates) are highly conserved ubiquitous eukaryotic homodimer proteins that interact, besides dynein and myosin 5a motor proteins, with a large (and still incomplete) number of proteins involved in diverse biological functions. Despite an earlier suggestion that LC8 light chains(More)
Molluscan catch muscles contain polypeptides of 110-120 kDa in size which have the same partial amino acid sequences as those of the myosin heavy chain (MHC). Here we provide evidence that these polypeptides are major components only of the catch-type muscles (their estimated molar ratio to MHC is approximately 1:1) and they are alternative products of the(More)
Light meromyosin (LMM), prepared by limited tryptic digestion of myosin, usually contains several polypeptide chains, LMM-A, LMM-B, and LMM-C in decreasing order of molecular weight estimated from sodium dodecyl sulfate-gel electrophoresis. Further limited tryptic digestion of LMM produces well defined fragments (Balint, M., Szilagyi, L., Fekete, Gy.,(More)
Alpha-helical coiled coils in muscle exemplify simplicity and economy of protein design: small variations in sequence lead to remarkable diversity in cellular functions. Myosin II is the key protein in muscle contraction, and the molecule's two-chain alpha-helical coiled-coil rod region--towards the carboxy terminus of the heavy chain--has unusual(More)
A 10 kDa dynein light chain (DLC), previously identified as a tail light chain of myosin Va, may function as a cargo-binding and/or regulatory subunit of both myosin and dynein. Here, we identify and characterize the binding site of DLC on myosin Va. Fragments of the human myosin Va tail and the DLC2 isoform were expressed, and their complex formation was(More)
We report here that the catch and striated adductor muscle myosin heavy-chain (MHC) isoforms of scallop (Argopecten irradians, previously Aequipecten irradians) are generated by alternative RNA splicing from a single gene. Scallop catch muscle cDNA and genomic DNA were amplified by PCR using primers based on the previously sequenced scallop striated muscle(More)
The N-terminal region of myosin's rod-like subfragment 2 (S2) joins the two heads of this dimeric molecule and is key to its function. Previously, a crystal structure of this predominantly coiled-coil region was determined for a short fragment (51 residues plus a leucine zipper) of the scallop striated muscle myosin isoform. In that study, the N-terminal(More)
We have compared the dimerization properties and coiled-coil stability of various recombinant fragments of scallop myosin around the head-rod junction. The heavy-chain peptide of the regulatory domain and its various extensions toward the alpha-helical rod region were expressed in Escherichia coli, purified, and reconstituted with the light chains. Rod(More)