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Articles 1 - 10 of 10

Full-Text Articles in Cell Biology

Hras Intracellular Trafficking And Signal Transduction, Jodi Ho-Jung Mckay Jan 2007

Hras Intracellular Trafficking And Signal Transduction, Jodi Ho-Jung Mckay

Retrospective Theses and Dissertations

Cancer, which is characterized by uncontrolled cell division and proliferation, is the second leading cause of death in the United States. Of these deaths, approximately 30% are the result of mutations in Ras protein. When activated, Ras propagates multiple signal transduction cascades and induces cell proliferation, differentiation, and apoptosis. Within the Ras subfamily, there are several isoforms of Ras which differ in their posttranslational modifications. The modifications include proteolytic cleavage of the CAAX box, farnesylation, and palmitoylation which act as plasma membrane anchors where most signal transduction takes place. This dissertation demonstrates that Ras endocytosis takes place through a novel ...


From Endomembrane To The Plasma Membrane: The Traffic, Signal Transduction And Micro-Localization Of H-Ras , Hui Zheng Jan 2006

From Endomembrane To The Plasma Membrane: The Traffic, Signal Transduction And Micro-Localization Of H-Ras , Hui Zheng

Retrospective Theses and Dissertations

Ras proteins are small G proteins that play key roles in many aspect of cell signal transduction. H-Ras is one of three isoforms of mammalian Ras protein that is best studied. The work presented in this dissertation describes how the carboxyl terminal lipid modifications affect the transportation, signal transduction and micro-localizations of H-Ras protein. The already known traffic pathway for H-Ras to the plasma membrane is Golgi mediated classical vesicular Transportation; However, we found the H-Ras transportation has many different features other than the classical pathway, and thereby discovered a new pathway for H-Ras targeting to the plasma membrane. This ...


Analysis Of A Nuclear Complex Of Proteins That Form A Spindle Matrix During Mitosis In Drosophila , Uttama Rath Jan 2005

Analysis Of A Nuclear Complex Of Proteins That Form A Spindle Matrix During Mitosis In Drosophila , Uttama Rath

Retrospective Theses and Dissertations

A spindle matrix is a macromolecular structure hypothesized to provide a stationary support or strut for the anchorage of motor proteins during force generation, microtubule sliding, and chromosome segregation in mitosis. Previous work in Drosophila has shown Skeletor, as the first putative molecular candidate of spindle matrix structure since it possesses many features consistent with the proposed spindle matrix structure.;We have identified two more putative spindle matrix candidate proteins, Chromator and Megator, using yeast two-hybrid interaction assay, cross-immunoprecipitation and immunocytochemistry. Chromator is a novel and essential chromodomain containing protein that interacts directly with Skeletor and extensively colocalizes with it ...


Investigation Of The Function Of Branching Enzymes I, Iia, And Iib In The Determination Of Amylopectin Structure And Regulation Of Starch Biosynthesis , Rebekah Suzanne Marsh Jan 2005

Investigation Of The Function Of Branching Enzymes I, Iia, And Iib In The Determination Of Amylopectin Structure And Regulation Of Starch Biosynthesis , Rebekah Suzanne Marsh

Retrospective Theses and Dissertations

Starch is one of the most abundant carbohydrates on earth serving vital roles as the primary energy reserve of plants, a significant source of calories in the human diet, and a renewable resource for other industrial applications. The multiplicity of starch biosynthetic enzymes is evolutionarily conserved in plants suggesting their functions are essential in starch biosynthesis. The overall goal of this research is to determine the specific molecular functions of the multiple starch branching enzyme (BE) isoforms in maize.;This dissertation first addresses what, if any, are the differences in enzymatic properties of BEIIa and BEIIb. Two polyclonal antisera were ...


The Essential Jil-1 Kinase Regulates Histone H3 Phosphorylation And Maintains Chromatin Structure In Drosophila , Weiguo Zhang Jan 2004

The Essential Jil-1 Kinase Regulates Histone H3 Phosphorylation And Maintains Chromatin Structure In Drosophila , Weiguo Zhang

Retrospective Theses and Dissertations

JIL-1 encodes a chromatin-associated tandem serine/threonine kinase in Drosophila melanogaster. JIL-1 predominantly associates with interbands on polytene chromosomes. It appears at higher levels on the X chromosome than on autosomes in males, and distributes about equally on all chromosomes in females. In addition, in males JIL-1 overlaps with the MSL (for male specific lethal) complex that specifically associates with the male X chromosome on which expression of most genes are upregulated.;We isolated JIL-1 mutants by inducing imprecise excision of an EP element inserted in JIL-1. We found that JIL-1 is required for viability of both females and males ...


Structural And Molecular Analysis Of Leech Neuronal Proteins, Calsensin And Filamin , Deepa V. Venkitaramani Jan 2004

Structural And Molecular Analysis Of Leech Neuronal Proteins, Calsensin And Filamin , Deepa V. Venkitaramani

Retrospective Theses and Dissertations

This thesis describes the structural and molecular analysis of two leech neuronal proteins, Calsensin and Filamin. Calsensin is an EF-hand calcium-binding protein expressed by a subset of peripheral sensory neurons which fasciculate into a single tract in the leech central nervous system. Calsensin is a 9 kD protein with two EF-hand calcium-binding motifs. Calsensin can multimerize via disulfide bridge formation involving the two cysteine residues in vitro. Furthermore, Calsensin shows differential gel migration depending on the presence or absence of calcium suggesting a conformational change upon calcium binding. Using multidimensional NMR spectroscopy we have determined the solution structure and backbone ...


Mechanisms Of Negative Regulation Of Protein Prenylation: Investigation Of Murine Guanylate-Binding Protein 1 , John Thomas Stickney Jan 2000

Mechanisms Of Negative Regulation Of Protein Prenylation: Investigation Of Murine Guanylate-Binding Protein 1 , John Thomas Stickney

Retrospective Theses and Dissertations

Covalent attachment of isoprenoid lipids to proteins is a post-translational modification that occurs on approximately 2% of all cellular proteins. Proteins that contain a CaaX motif as their final four amino acids are presumed to be targets for the addition of C15 or C20 isoprenoids by farnesyl transferase (FTase) or geranylgeranyl transferase I (GGTase I) respectively. This modification is generally believed to occur stoichiometrically, and irreversibly, in vivo. Thus, if prenylation is to be regulated, this control must occur prior to lipid addition. At the moment, there is little evidence that the enzymatic activity of prenyl transferases can be modulated ...


Effects Of Altering Titin Expression On Myofibril Assembly In A Skeletal Muscle Cell Line , Qunfeng Dong Jan 2000

Effects Of Altering Titin Expression On Myofibril Assembly In A Skeletal Muscle Cell Line , Qunfeng Dong

Retrospective Theses and Dissertations

Titin is a giant muscle protein that spans the distance from the Z line to the M line in sarcomeres of striated muscle myofibrils. One of the functions proposed for titin is that it could act as a molecular scaffold to direct sarcomere assembly. To investigate this role of titin, titin expression was transiently altered in the cultured mouse skeletal muscle cell line C2C12 by either a dominant-negative approach or an antisense mRNA approach. The time course of myofibril assembly was monitored by immunofluorescence labeling with antibodies to actin, alpha-actinin, titin, and myosin from 1 to 5 d after myoblast ...


The Contributions Of The Hras C-Terminus And Its Lipid Modifications To Hras Signal Transduction Events And Membrane Binding , Michelle Ann Booden Jan 2000

The Contributions Of The Hras C-Terminus And Its Lipid Modifications To Hras Signal Transduction Events And Membrane Binding , Michelle Ann Booden

Retrospective Theses and Dissertations

In the GTP bound state, Ras proteins activate multiple downstream effector proteins, the combination of which regulate cell growth, differentiation, and changes in cell shape. However, Ras proteins must undergo C-terminal lipidation before they can support biological activity. Specifically, the C-terminus of the HRas protein must be modified by a farnesyl at Cys186 and two palmitates at Cys181 and Cys184. The current paradigm suggests that palmitate is not attached without prior farnesyl addition and that these post-translational lipid modifications are only necessary for membrane association. However, emerging evidence suggests that the C-terminus and its lipid modifications may also be responsible ...


Fatty Acid Modification Of Cells In Culture By Overexpression Of Exogenous Desaturases , Travis Jay Knight Jan 1999

Fatty Acid Modification Of Cells In Culture By Overexpression Of Exogenous Desaturases , Travis Jay Knight

Retrospective Theses and Dissertations

COS-1 cells were transfected transiently with expression vectors encoding stearoyl-acyl-carrier-protein desaturase (SACPD) from castor bean, stearoyl-CoA desaturase (SCD) from mice, and a control vector containing SACPD cDNA in reverse orientation. The hypothesis was that both exogenous desaturases would be active in COS-1 cells, thereby increasing the proportion of monounsaturated fatty acids produced by the cells. Messenger RNA and anti-myc immunoreactive proteins were detected at 12 and 24 hours post-transfection respectively and increased through 48 hours post-transfection. When acetate was used as the fatty acid precursor in cultures for a 24-hour period starting 24 hours post-transfection, the ratio of monounsaturated to ...