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Research was conducted to examine how Ca2+ or Mg2+ bound at the high-affinity cation binding site in F-actin modulates the dynamic response of the filaments to ATP hydrolysis by attached myosin head fragments (S1). Luminescence calculations were performed under anaerobic conditions while steady-state fluorescence emission anisotropy spectra and steady-state phosphorescence emission anisotropy and intensity decay studies were conducted according to previously reported protocols. Results indicate that the long axis torsional rigidity of F-actin plays an important role in modulating the dynamic response of the filaments to ATP hydrolysis by S1.

A study on G protein-coupled receptors and the attenuation of G protein signaling describes the use of site-directed mutagenesis in defining sites within the cytoplasmic loops of bovine rhodopsin that are critical for its interaction with the visual rod arrestin. Results of the experiment suggest for the first time the participation of specific residues in cytoplasmic loops I and II in the formation of a contact site for arrestin.

Research was conducted to prove that the thermally driven motion of the sidearms causes an entropic brush that maintains interfilament spacing. A long-range repulsive force near isolated neurofilaments was observed through the exclusion of large molecules and direct force measurements with atomic force microscopy. Results indicate that neurofilament sidearms form an entropic brush which provides a controling mechanism for interfilament spacing.

Circular dichroism and nuclear magnetic resonance spectroscopy were performed to study the structures of 14- and 29-residue synthetic peptides designated NLEKG14 and NLEKG29, respectively, which are model peptides that represent the alpha-helical regions of intermediate filaments (IFs). The results indicated that such regions in the IFs appear to be exceptionally stable. There is also evidence that significant parts of the rod regions of the IFs appear to be occupied by conformations other than alpha-helix.

Neurofilament proteins and the neuron-specific microtubule-associated protein tau are phosphorylated in vivo at sites conforming to the phosphorylation consensus motif of the cell-cycle-control protein kinase, p[34.sup.cdc2]-cyclin. Abnormalities in the phosphorylation of these proteins are associated with neurodegenerative disorders, such as amylotrophic lateral sclerosis and Alzheimer's disease. A cdc2-like kinase composed of cyclin-dependent kinase 5 (cdk5) and a brain-specific regulatory subunit is proposed to be responsible for the cdc2-like phosphorylation of these neuronal proteins.

Titin and nebulin are giant muscle proteins, both of which are approximately 1 [[micro]meter] long and are composed of many repeating domains. Titin domains resemble type III fibronectin and C-2 immunoglobulins. Both proteins are likely to be involved in specifying and stabilizing the highly ordered structure of muscle, probably by acting as 'protein rulers' to regulate the assembly of myosin and actin filaments precisely.

The bonding of Mg(2+)-ATP and myofibrils in the presence of P3-(1-(2-nitrophenyl)ethyl)adenosine 5'-triphosphate (caged ATP) was studied using a quench flow technique. The observation of single turnovers of (gamma-32P)ATP hydrolysis revealed that ADP had an inhibition constant of 145 micromoles. The study revealed a lower rate of ATP binding caused by the preventive effects of caged ATP on bonding of ATP and fibers.

Kinetics of second-order were used during the re-formation of actin filaments after they were fragmented by sonication when ATP and phallodin were present. Cell motile occurrences which need resetting of filament networks may require the annealing of actin filaments in vivo. Quick annealing of tiny polymers of actin may be a feasible pathway for resetting filament network.

UD-CG 212 Cl, a novel pharmacological instrument, aids myofilament activation with high levels of affinity. The functioning of myofilament activation can be gauged by intricately examining myofibrillar conformations which are influenced by the pharmacological tool. Myocardial ischemia is subjected to clinical treatment with low levels of UD-CG 212 Cl. Myocardial ischemia causes the progressive rise in inorganic phosphate. Acute myocardial ischemia is produced to reveal the good influences of UD-CG 212 Cl on the myofilament.

The first quantitative study of nuclear localization of rabies P-protein (RPP) is presented which identifies a second CRM-1-dependent NES in the rabies P-protein C-terminal domain (RPPCTD). It is hypothesized that the CTD acts as a novel molecular switch to regulate trafficking of RPP.

A homology model of Escherichia coli transporter ProP with 12-transmembrane (TM) helices and cytoplasmic termini was created to explore the structure and function of ProP residues Q415-E440, predicted to include TM XII. The study result define the position of ProP TM XII within the membrane and reveal the dimerization interface and show that the structure of TM XII influences the osmolality at which ProP activates.

The role of the C-terminal segment on the stability and tetrameric assembly of the channel protein were evaluated using the C-terminal deletion channel mutants obtained from chymotrypin cleavage of full-length 1-160 KcsA. It was found that lack of cytoplasmic C-terminal domain of KcsA and, most critically, the 120-124 sequence stretch prevents tetramization of monomeric channel subunits in an Escherichia coli expression system.