The long term goals of the proposed research are to gain a better understanding of the role of transverse tubules in the process of excitation/contraction coupling in muscle and to understand how that process is regulated by pharmacologically important and clinically significant ions and drugs. The transverse tubules play a pivotal role in excitation/contraction coupling and abnormalities of the transverse tubules may be important in muscular dystrophy. These membranes have very interesting pharmacological and biochemical characteristics, including a preponderance of Ca2+ antagonist drug binding sites, a high level of cholesterol, and a highly active, unique Mg2+-ATPase which may play a key role in excitation/contraction coupling.
The specific aims are to identify, purify, characterize in terms of possible physiological function, and affinity label the Mg2+-ATPase. Polyclonal antibodies will be raised to the subunits of the Mg2+ -Atpase. N-terminal sequencing of the purified subunits as well as enzymatic and chemical fragmentation followed by purified of peptides for sequencing will be performed. From the protein sequence obtained, oligonucleotide probes will be made to allow the identification of the cDNA coding for the Mg2+ -ATPase and the entire amino acid sequence deduced from the cDNA sequence. A membrane spanning model will be proposed based on hydropathy plots and labeling of sites on the cytoplasmic face of the protein. This ATPase will be compared structurally and functionally to other ATPases. The Mg2+ -ATPase may be a member of a previously unknown class of ATPases, and structural comparisons will be invaluable in the determination of essential and therefore conserved, domains. The techniques utilized in this work are centrifugation for native gel electrophoresis and sucrose density centrifugation for isolation of the enzyme, trypsin and cyanogen bromide fragmentation, reversed phase HPLC, and amino acid analysis and gas phase sequencing for the determination of the amino terminal sequence of the protein and generated peptide fragments. Techniques of cDNA cloning and sequencing will be used to determine the entire sequence of the gene coding for the Mg2+ -ATPase. This research will supply important information about a transverse tubule component involved in excitation/contraction coupling which will lead to a better understanding of this physiologically crucial process.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
5R01AR038576-04
Application #
3158637
Study Section
Physiology Study Section (PHY)
Project Start
1989-03-01
Project End
1994-02-28
Budget Start
1992-03-01
Budget End
1993-02-28
Support Year
4
Fiscal Year
1992
Total Cost
Indirect Cost
Name
University of Cincinnati
Department
Type
Schools of Medicine
DUNS #
City
Cincinnati
State
OH
Country
United States
Zip Code
45221
Smith Jr, T M; Kirley, T L; Hennessey, T M (1997) A soluble ecto-ATPase from Tetrahymena thermophila: purification and similarity to the membrane-bound ecto-ATPase of smooth muscle. Arch Biochem Biophys 337:351-9
Kirley, T L (1997) Complementary DNA cloning and sequencing of the chicken muscle ecto-ATPase. Homology with the lymphoid cell activation antigen CD39. J Biol Chem 272:1076-81
Stout, J G; Kirley, T L (1996) Control of cell membrane ecto-ATPase by oligomerization state: intermolecular cross-linking modulates ATPase activity. Biochemistry 35:8289-98
Stout, J G; Strobel, R S; Kirley, T L (1995) Properties of and proteins associated with the extracellular ATPase of chicken gizzard smooth muscle. A monoclonal antibody study. J Biol Chem 270:11845-50
Stout, J G; Strobel, R S; Kirley, T L (1995) Identification and immunolocalization of ecto-ATPDase in chicken stomach. Biochem Mol Biol Int 36:529-35
Stout, J G; Kirley, T L (1995) Inhibition of purified chicken gizzard smooth muscle ecto-ATPAse by P2 purinoceptor antagonists. Biochem Mol Biol Int 36:927-34
Stout, J G; Kirley, T L (1994) Tissue distribution of ecto-Mg-ATPase in adult and embryonic chicken. Biochem Mol Biol Int 32:745-53
Stout, J G; Kirley, T L (1994) Purification and characterization of the ecto-Mg-ATPase of chicken gizzard smooth muscle. J Biochem Biophys Methods 29:61-75
Peng, M; Fan, H; Kirley, T L et al. (1994) Structural diversity of triadin in skeletal muscle and evidence of its existence in heart. FEBS Lett 348:17-20
Stout, J G; Brittsan, A; Kirley, T L (1994) Brain ECTO-Mg-ATPase is not the neural cell adhesion molecule. Biochem Mol Biol Int 33:1091-8

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